The Gale Encyclopedia of Neurological Disorders [Volume 1, 1 ed.] 9780787691509, 0-7876-9150-X, 0787691518, 0787691526

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The GALE

ENCYCLOPEDIA of

NEurological Disorders

The GALE

ENCYCLOPEDIA of

NEurological Disorders VO L U M E

1 A-L

S TAC E Y L . C H A M B E R L I N , B R I G H A M N A R I N S , E D I TO R S

The Gale Encyclopedia of Neurological Disorders

Project Editors Stacey L. Chamberlin, Brigham Narins

Rights Acquisitions Management Margaret Chamberlain, Jackie Jones, Shalice Shah-Caldwell

Editorial Erin Watts

Imaging and Multimedia Randy Basset, Lezlie Light, Dan Newell, Robyn V. Young

Editorial Support Services Andrea Lopeman

Composition and Electronic Prepress Evi Seoud, Mary Beth Trimper Manufacturing Wendy Blurton, Dorothy Maki

Product Design Michelle DiMercurio, Tracey Rowens, Kate Scheible

Indexing Services Synapse

©2005 Thomson Gale, a part of The Thomson Corporation. Thomson and Star Logo are trademarks and Gale is a registered trademark used herein under license. For more information, contact The Gale Group, Inc. 27500 Drake Rd. Farmington Hills, MI 48331-3535 Or you can visit our Internet site at http://www.gale.com ALL RIGHTS RESERVED No part of this work covered by the copyright hereon may be reproduced or used in any form or by any means—graphic, electronic, or mechanical, including photocopying, recording, taping, Web distribution, or information storage retrieval systems—without the written permission of the publisher.

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LIBRARY OF CONGRESS CATALOGING-IN-PUBLICATION DATA The Gale encyclopedia of neurological disorders / Stacey L. Chamberlin, Brigham Narins, editors. p. ; cm. Includes bibliographical references and index. ISBN 0-7876-9150-X (set hardcover : alk. paper) — ISBN 0-7876-9151-8 (v. 1) — ISBN 0-7876-9152-6 (v. 2) 1. Neurology—Encyclopedias. [DNLM: 1. Nervous System Diseases—Encyclopedias—English. 2. Nervous System Diseases—Popular Works. WL 13 G151 2005] I. Title: Encyclopedia of neurological disorders. II. Chamberlin, Stacey L. III. Narins, Brigham, 1962– IV. Gale Group. RC334.G34 2005 616.8'003—dc22

2004021644

This title is also available as an e-book. ISBN 0-7876-9160-7 (set) Contact your Gale sales representative for ordering information. Printed in the United States of America 10 9 8 7 6 5 4 3 2 1

CONTENTS

List of Entries ................................................vii Introduction ..................................................xiii Advisory Board..............................................xv Contributors .................................................xvii Entries Volume 1: A–L........................................................1 Volume 2: M–Z...................................................511

Glossary .......................................................941 General Index...............................................973

GALE ENCYCLOPEDIA OF NEUROLOGICAL DISORDERS

v

LIST OF ENTRIES

❙A

Abulia Acetazolamide Acupuncture Acute disseminated encephalomyelitis Adrenoleukodystrophy Affective disorders Agenesis of the corpus callosum Agnosia AIDS Alcohol-related neurological disease Alexander disease Alpers’ disease Alternating hemiplegia Alzheimer disease Amantadine Amnestic disorders Amyotrophic lateral sclerosis Anatomical nomenclature Anencephaly Aneurysms Angelman syndrome Angiography Anosmia Anticholinergics Anticonvulsants Antiepileptic drugs Antimigraine medications Antiparkinson drugs Antiviral drugs Anxiolytics Aphasia Apraxia Arachnoid cysts Arachnoiditis Arnold-Chiari malformation Arteriovenous malformations Aspartame Asperger’s disorder Assistive mobile devices Ataxia-telangiectasia Ataxia Atomoxetine Attention deficit hyperactivity disorder Autism Autonomic dysfunction

❙B

Back pain Bassen-Kornzweig syndrome Batten disease Behçet disease Bell’s palsy Benign positional vertigo Benzodiazepines Beriberi Binswanger disease Biopsy Blepharospasm Bodywork therapies Botulinum toxin Botulism Brachial plexus injuries Brain anatomy Brain and spinal tumors Brown-Séquard syndrome

❙C

Canavan disease Carbamazepine Carotid endarterectomy Carotid stenosis Carpal tunnel syndrome Catechol-O-methyltransferase inhibitors Central cord syndrome Central nervous system Central nervous system stimulants Central pain syndrome Cerebellum Cerebral angiitis Cerebral cavernous malformation Cerebral circulation Cerebral dominance Cerebral hematoma Cerebral palsy Channelopathies Charcot-Marie-Tooth disorder Cholinergic stimulants Cholinesterase inhibitors Chorea

GALE ENCYCLOPEDIA OF NEUROLOGICAL DISORDERS

Chronic inflammatory demyelinating polyneuropathy Clinical trials Congenital myasthenia Congenital myopathies Corpus callosotomy Corticobasal degeneration Craniosynostosis Craniotomy Creutzfeldt-Jakob disease CT scan Cushing syndrome Cytomegalic inclusion body disease

❙D

Dandy-Walker syndrome Deep brain stimulation Delirium Dementia Depression Dermatomyositis Devic syndrome Diabetic neuropathy disease Diadochokinetic rate Diazepam Dichloralphenazone Dichloralphenazone, Isometheptene, and Acetaminophen Diencephalon Diet and nutrition Disc herniation Dizziness Dopamine receptor agonists Dysarthria Dysesthesias Dysgeusia Dyskinesia Dyslexia Dyspraxia Dystonia

❙E

Electric personal assistive mobility devices

vii

List of Entries

Electroencephalography Electromyography Empty sella syndrome Encephalitis and Meningitis Encephalitis lethargica Encephaloceles Encephalopathy Endovascular embolization Epidural hematoma Epilepsy Exercise

❙F

Fabry disease Facial synkinesis Fainting Fatigue Febrile seizures Felbamate Fisher syndrome Foot drop Fourth nerve palsy Friedreich ataxia

❙G

Gabapentin Gaucher disease Gene therapy Gerstmann-Straussler-Scheinker disease Gerstmann syndrome Glossopharyngeal neuralgia Glucocorticoids Guillain-Barré syndrome

❙H

Hallucination Headache Hearing disorders Hemianopsia Hemifacial spasm Hereditary spastic paraplegia Holoprosencephaly HTLV-1 Associated Myelopathy Huntington disease Hydantoins Hydranencephaly Hydrocephalus Hydromyelia Hypersomnia Hypotonia Hypoxia

❙I

Idiopathic neuropathy viii

Inclusion body myositis Incontinentia pigmenti Infantile spasms Inflammatory myopathy Interferons

❙J

Multiple sclerosis Multiple system atrophy Muscular dystrophy Myasthenia, congenital Myasthenia gravis Myoclonus Myofibrillar myopathy Myopathy Myotonic dystrophy

Joubert syndrome

❙N

❙K

Kennedy’s disease Klippel Feil syndrome Krabbe disease Kuru

❙L

Lambert-Eaton myasthenic syndrome Laminectomy Lamotrigine Learning disorders Lee Silverman voice treatment Leigh disease Lennox-Gastaut syndrome Lesch-Nyhan syndrome Leukodystrophy Levetiracetam Lewy body dementia Lidocaine patch Lissencephaly Locked-in syndrome Lupus Lyme disease

❙M

Narcolepsy Nerve compression Nerve conduction study Neurofibromatosis Neuroleptic malignant syndrome Neurologist Neuromuscular blockers Neuronal migration disorders Neuropathologist Neuropsychological testing Neuropsychologist Neurosarcoidosis Neurotransmitters Niemann-Pick Disease

❙O

Occipital neuralgia Olivopontocerebellar atrophy Opsoclonus myoclonus Organic voice tremor Orthostatic hypotension Oxazolindinediones

❙P

Machado-Joseph disease Magnetic resonance imaging (MRI) Megalencephaly Melodic intonation therapy Ménière’s disease Meninges Mental retardation Meralgia paresthetica Metachromatic leukodystrophy Microcephaly Mitochondrial myopathies Modafinil Moebius syndrome Monomelic amyotrophy Motor neuron diseases Movement disorders Moyamoya disease Mucopolysaccharidoses Multi-infarct dementia Multifocal motor neuropathy

Pain Pallidotomy Pantothenate kinase-associated neurodegeneration Paramyotonia congenita Paraneoplastic syndromes Parkinson’s disease Paroxysmal hemicrania Parsonage-Turner syndrome Perineural cysts Periodic paralysis Peripheral nervous system Peripheral neuropathy Periventricular leukomalacia Phantom limb Pharmacotherapy Phenobarbital Pick disease Pinched nerve Piriformis syndrome Plexopathies Poliomyelitis

GALE ENCYCLOPEDIA OF NEUROLOGICAL DISORDERS

❙R

Radiation Radiculopathy Ramsay-Hunt syndrome type II Rasmussen’s encephalitis Reflex sympathetic dystrophy Refsum disease Repetitive motion disorders Respite Restless legs syndrome Rett syndrome Reye syndrome

❙S

Sandhoff disease Schilder’s disease Schizencephaly Schizophrenia Sciatic neuropathy Sciatica Seizures Septo-optic dysplasia Shaken baby syndrome Shingles Single Proton Emission Computed Tomography

Sixth nerve palsy Sjogren-Larsson Syndrome Sleep apnea Social workers Sodium oxybate Sotos syndrome Spasticity Speech synthesizer Spina bifida Spinal cord infarction Spinal cord injury Spinal muscular atrophy Spinocerebellar ataxia Status epilepticus Stiff person syndrome Striatonigral degeneration Stroke Sturge-Weber syndrome Stuttering Subacute sclerosing panencephalitis Subdural hematoma Succinamides Swallowing disorders Sydenham’s chorea Syringomyelia

❙T

Tabes dorsalis Tay-Sachs disease Temporal arteritis Temporal lobe epilepsy Tethered spinal cord syndrome Third nerve palsy Thoracic outlet syndrome Thyrotoxic myopathy Tiagabine Todd’s paralysis Topiramate Tourette syndrome Transient global amnesia Transient ischemic attack Transverse myelitis Traumatic brain injury

GALE ENCYCLOPEDIA OF NEUROLOGICAL DISORDERS

List of Entries

Polymyositis Pompe disease Porencephaly Positron emission tomography (PET) Post-polio Syndrome Primary lateral sclerosis Primidone Prion diseases Progressive multifocal leukoencephalopathy Progressive supranuclear palsy Pseudobulbar palsy Pseudotumor cerebri

Tremors Trigeminal neuralgia Tropical spastic paraparesis Tuberous sclerosis

❙U

Ulnar neuropathy Ultrasonography

❙V

Valproic acid and divalproex sodium Vasculitic neuropathy Vasculitis Ventilatory assistance devices Ventricular shunt Ventricular system Vertebrobasilar disease Vestibular schwannoma Visual disturbances Vitamin/nutritional deficiency Von Hippel-Lindau disease

❙W

Wallenberg syndrome West Nile virus infection Whiplash Whipple’s Disease Williams syndrome Wilson disease

❙Z

Zellweger syndrome Zonisamide

ix

PLEASE READ—IMPORTANT INFORMATION

The Gale Encyclopedia of Neurological Disorders is a medical reference product designed to inform and educate readers about a wide variety of diseases, syndromes, drugs, treatments, therapies, and diagnostic equipment. Thomson Gale believes the product to be comprehensive, but not necessarily definitive. It is intended to supplement, not replace, consultation with a physician or other healthcare practitioner. While Thomson Gale has made substantial efforts to provide information that is accurate,

comprehensive, and up-to-date, Thomson Gale makes no representations or warranties of any kind, including without limitation, warranties of merchantability or fitness for a particular purpose, nor does it guarantee the accuracy, comprehensiveness, or timeliness of the information contained in this product. Readers are advised to seek professional diagnosis and treatment for any medical condition, and to discuss information obtained from this book with their healthcare providers.

GALE ENCYCLOPEDIA OF NEUROLOGICAL DISORDERS

xi

INTRODUCTION

The Gale Encyclopedia of Neurological Disorders (GEND) is a one-stop source for medical information that covers diseases, syndromes, drugs, treatments, therapies, and diagnostic equipment. It keeps medical jargon to a minimum, making it easier for the layperson to use. The Gale Encyclopedia of Neurological Disorders presents authoritative and balanced information and is more comprehensive than single-volume family medical guides.

• Precautions • Side effects • Interactions • Resources • Key terms Treatments • Definition

SCOPE

Almost 400 full-length articles are included in The Gale Encyclopedia of Neurological Disorders. Articles follow a standardized format that provides information at a glance. Rubrics include: Diseases • Definition • Description • Demographics • Causes and symptoms • Diagnosis • Treatment team • Treatment • Recovery and rehabilitation • Clinical trials • Prognosis • Special concerns • Resources

• Purpose • Precautions • Description • Preparation • Aftercare • Risks • Normal results • Resources • Key terms INCLUSION CRITERIA

A preliminary topic list was compiled from a wide variety of sources, including professional medical guides, consumer guides, and textbooks and encyclopedias. The advisory board, made up of seven medical and healthcare experts, evaluated the topics and made suggestions for inclusion. Final selection of topics to include was made by the medical advisors in conjunction with Gale editors.

• Key terms Drugs • Definition • Purpose • Description • Recommended dosage

ABOUT THE CONTRIBUTORS

The essays were compiled by experienced medical writers, physicians, nurses, and pharmacists. GEND medical advisors reviewed most of the completed essays to insure that they are appropriate, up-to-date, and medically accurate.

GALE ENCYCLOPEDIA OF NEUROLOGICAL DISORDERS

xiii

Introduction

HOW TO USE THIS BOOK

The Gale Encyclopedia of Neurological Disorders has been designed with ready reference in mind: • Straight alphabetical arrangement allows users to locate information quickly. • Bold faced terms function as print hyperlinks that point the reader to full-length entries in the encyclopedia. • A list of key terms is provided where appropriate to define unfamiliar words or concepts used within the context of the essay. • Cross-references placed throughout the encyclopedia direct readers to where information on subjects without their own entries can be found. Cross-references are also used to assist readers looking for information on diseases that are now known by other names; for example, there is a cross-

xiv

reference for the rare childhood disease commonly known as Hallervorden-Spatz disease that points to the entry entitled Pantothenate kinase-associated neurodegeneration. • A Resources section directs users to sources of further information, which include books, periodicals, websites, and organizations. • A glossary is included to help readers understand unfamiliar terms. • A comprehensive general index allows users to easily target detailed aspects of any topic. GRAPHICS

The Gale Encyclopedia of Neurological Disorders is enhanced with over 100 images, including photos, tables, and customized line drawings.

GALE ENCYCLOPEDIA OF NEUROLOGICAL DISORDERS

ADVISORY BOARD An advisory board made up of prominent individuals from the medical and healthcare communities provided invaluable assistance in the formulation of this encyclopedia. They defined the scope of coverage and reviewed individual entries for accuracy and accessibility; in some cases they contributed entries themselves. We would therefore like to express our great appreciation to them:

Laurie Barclay, MD Neurologist and Writer Tampa, FL

Brenda Wilmoth Lerner, RN Nurse, Writer, and Editor London, UK

F. James Grogan, PharmD Pharmacist, Clinician, Writer, Editor, and Consultant Swansea, IL

Yuen T. So, MD, PhD Associate Professor Clinical Neurosciences Stanford University School of Medicine Stanford, CA

Joel C. Kahane, PhD Professor, Director of the Anatomical Sciences Laboratory The School of Audiology and Speech-Language Pathology The University of Memphis Memphis, TN

GALE ENCYCLOPEDIA OF NEUROLOGICAL DISORDERS

Roy Sucholeiki, MD Professor, Director of the Comprehensive Epilepsy Program Department of Neurology Loyola University Health System Chicago, IL Gil I. Wolfe, MD Associate Professor Department of Neurology The University of Texas Southwestern Medical Center Dallas, TX

xv

CONTRIBUTORS

Lisa Maria Andres, MS, CGC Certified Genetic Counselor and Medical Writer San Jose, CA Paul Arthur Science writer London, England Bruno Verbeno Azevedo Espirito Santo University Vitória, Brazil Deepti Babu, MS, CGC Genetic Counselor Marshfield Clinic Marshfield, WI Laurie Barclay, MD Neurologist and writer Tampa, FL Julia Barrett Science Writer Madison, WI

Robert G. Best, PhD Director Division of Genetics University of South Carolina School of Medicine Columbia, SC Michelle Lee Brandt Medical Writer San Francisco, CA Dawn J. Cardeiro, MS, CGC Genetic Counselor Fairfield, PA Francisco de Paula Careta Espirito Santo University Vitória, Brazil Rosalyn Carson-DeWitt, MD Physician and Medical Writer Durham, NC

James Paul Dworkin, PhD Professor Department of Otolaryngology, Voice/Speech Pathology Program and Laboratory Wayne State University Detroit, MI L. Fleming Fallon, Jr., MD, DrPH Professor Department of Public Health Bowling Green State University Bowling Green, OH Antonio Farina, MD, PhD Department of Embryology, Obstetrics, and Gynecology University of Bologna Bologna, Italy Kevin Fitzgerald Science Writer and Journalist South Windsor, CT

Stacey L. Chamberlin Science Writer and Editor Fairfax, VA

Paula Anne Ford-Martin Medical Writer Warwick, RI

Maria Basile, PhD Medical Writer Roselle, NJ

Bryan Richard Cobb, PhD Institute for Molecular and Human Genetics Georgetown University Washington, D.C.

Lisa A. Fratt Medical Writer Ashland, WI

Tanja Bekhuis, PhD Science Writer and Psychologist TCB Research Boalsburg, PA

Adam J. Cohen, MD Craniofacial Surgery, Eyelid and Facial Plastic Surgery, Neuro-Ophthalmology Downers Grove, IL

Juli M. Berwald, PhD Geologist (Ocean Sciences) Chicago, Illinois

Tish Davidson, AM Medical Writer Fremont, CA

Danielle Barry, MS Graduate Assisstant Center of Alcohol Studies Rutgers University Piscataway, NJ

GALE ENCYCLOPEDIA OF NEUROLOGICAL DISORDERS

Rebecca J. Frey, PhD Freelance Medical Writer New Haven, CT Sandra L. Friedrich, MA Science Writer Clinical Psychology Chicago, IL Sandra Galeotti, MS Science Writer Sao Paulo, Brazil xvii

Contributors

Larry Gilman, PhD Electrical Engineer and Science Writer Sharon, VT Laith Farid Gulli, MD Consulting Psychotherapist Lathrup Village, MI Stephen John Hage, AAAS, RT(R), FAHRA Medical Writer Chatsworth, CA Brook Ellen Hall, PhD Science Writer Loomis, CA Dan Harvey Medical Writer Wilmington, DE Hannah M. Hoag, MSc Science and Medical Writer Montreal, Canada Brian Douglas Hoyle, PhD Microbiologist Nova Scotia, Canada Cindy L. Hunter, CGC Genetic Counselor Medical Genetics Department Indiana University School of Medicine Indianapolis, IN Alexander I. Ioffe, PhD Senior Scientist Geological Institute of the Russian Academy of Sciences Moscow, Russia Holly Ann Ishmael, MS, CGC Genetic Counselor The Children’s Mercy Hospital Kansas City, MO Joel C. Kahane, PhD Professor, Director of the Anatomical Sciences Laboratory The School of Audiology and Speech-Language Pathology The University of Memphis Memphis, TN xviii

Kelly Karpa, PhD, RPh Assistant Professor Department of Pharmacology Pennsylvania State University College of Medicine Hershey, PA Karen M. Krajewski, MS, CGC Genetic Counselor, Assistant Professor of Neurology Wayne State University Detroit, MI Judy Leaver, MA Behavioral Health Writer and Consultant Washington, D.C. Adrienne Wilmoth Lerner University of Tennessee College of Law Knoxville, TN Brenda Wilmoth Lerner, RN Nurse, Writer, and Editor London, UK K. Lee Lerner Fellow (rt) Science Policy Institute London, UK Agnieszka Maria Lichanska, PhD Department of Microbiology and Parasitology University of Queensland Brisbane, Australia Peter T. Lin, MD Research Assistant Member: American Academy of Neurology, American Association of Electrodiagnostic Medicine Department of Biomagnetic Imaging University of California, San Francisco Foster City, CA Iuri Drumond Louro, MD, PhD Adjunct Professor Human and Molecular Genetics Espirito Santo University Vitória, Brazil

Nicole Mallory, MS, PA-C Medical Student Wayne State University Detroit, MI Igor Medica, MD, PhD Assistant Professor School of Medicine University of Rijeka Pula, Croatia Michael Mooney, MA, CAC Consultant Psychotherapist Warren, MI Alfredo Mori, MD, FACEM, FFAEM Emergency Physician The Alfred Hospital Victoria, Australia Oxford’s Program in EvidenceBased Health Care University of Oxford Oxford, England Marcos do Carmo Oyama Espirito Santo University Vitória, Brazil Greiciane Gaburro Paneto Espirito Santo University Vitória, Brazil Borut Peterlin, MD, PhD Neurologist; Consultant Clinical Geneticist; Director Division of Medical Genetics University Medical Center Lubiana, Slovenia Toni I. Pollin, MS, CGC Research Analyst Division of Endocrinology, Diabetes, and Nutrition University of Maryland School of Medicine Baltimore, MD J. Ricker Polsdorfer, MD Medical Writer Phoenix, AZ Scott J. Polzin, MS, CGC Medical Writer Buffalo Grove, IL Jack Raber, PharmD Principal Clinipharm Services Seal Beach, CA

GALE ENCYCLOPEDIA OF NEUROLOGICAL DISORDERS

Amie Stanley, MS Genetic Counselor Medical Genetics The Cleveland Clinic Cleveland, OH

Richard Robinson Medical Writer Tucson, AZ

Constance K. Stein, PhD Director of Cytogenetics, Assistant Director of Molecular Diagnostics SUNY Upstate Medical University Syracuse, NY

Jennifer Ann Roggenbuck, MS, CGC Genetic Counselor Hennepin County Medical Center Minneapolis, MN Nancy Ross-Flanigan Science Writer Belleville, MI Stephanie Dionne Sherk Freelance Medical Writer University of Michigan Ann Arbor, MI Lee Alan Shratter, MD Consulting Radiologist Kentfield, CA Genevieve T. Slomski, PhD Medical Writer New Britain, CT

Roger E. Stevenson, MD Senior Clinical Geneticist, Senior Clinical Laboratory Geneticist Greenwood Genetic Center Greenwood, SC Roy Sucholeiki, MD Professor, Director of the Comprehensive Epilepsy Program Department of Neurology Loyola University Health System Chicago, IL Kevin M. Sweet, MS, CGC Cancer Genetic Counselor James Cancer Hospital, Ohio State University Columbus, OH

GALE ENCYCLOPEDIA OF NEUROLOGICAL DISORDERS

Contributors

Robert Ramirez, DO Medical Student University of Medicine and Dentistry of New Jersey Stratford, NJ

David Tulloch Science Writer Wellington, New Zealand Carol A. Turkington Medical Writer Lancaster, PA Samuel D. Uretsky, PharmD Medical Writer Wantagh, NY Chitra Venkatasubramanian, MBBS, MD (internal medicine) Resident in Neurology Department of Neurology and Neurosciences Stanford University Stanford, CA. Bruno Marcos Verbeno Espirito Santo University Vitória, Brazil Beatriz Alves Vianna Espirito Santo University Vitória, Brazil

xix

A Abetalipoproteinemia see BassenKornzweig syndrome

Key Terms Basal ganglia A group of brain structures that are responsible for movement.

❙ Abulia Definition

Abulia is a state in which an individual seems to have lost will or motivation.

Dopamine A brain chemical (neurotransmitter) responsible for carrying messages throughout the nervous system, particularly messages regarding movement. Frontal lobe The area of the brain responsible for higher thinking.

Description Abulia is not a separate condition; rather, it is a symptom associated with various forms of brain injury. It may occur in association with a variety of conditions, including stroke, brain tumor, traumatic brain damage, bleeding into the brain, and exposure to toxic substances.

Causes and symptoms Some research suggests that abulia occurs due to malfunction of the brain’s dopamine-dependent circuitry. Injuries to the frontal lobe (the area of the brain responsible for higher thinking) and/or the basal ganglia (the area of the brain responsible for movement) can interfere with an individual’s ability to initiate speech, movement, and social interaction. Abulia has been noted in patients who have suffered brain injuries due to stroke, bleeding into the brain from a ruptured aneurysm, trauma, brain tumor, neurological disease (such as Parkinson’s disease), psychiatric condition (such as severe depression or schizophrenia), and exposure to toxic substances (such as cyclosporin-A). An individual with abulia may not appear to have much will or motivation to pursue activities or initiate conversation. Such an individual may appear apathetic, disinterested, asocial, quiet or mute, physically slowed or still (hypokinetic), and emotionally remote.

Diagnosis Abulia is not an individual diagnosis; it is a symptom that usually occurs as part of a constellation of symptoms accompanying a specific disorder. Diagnosis of the underlying disorder depends on the kinds of symptoms that co-exist with abulia. Psychiatric interview, magnetic resonance imaging (MRI), ultrasound, or computed tomography (CT) imaging of the brain, EEG, blood tests, and neurological testing may all be used to diagnose an underlying condition.

Treatment team Treatment of abulia is usually part of a program of general rehabilitation for the symptoms accompanying the underlying condition. A neurologist or psychiatrist may lead a treatment team. Other professionals that may be involved include physical therapists, occupational therapists, recreational therapists, and speech and language therapists.

Treatment There are no specific treatments for abulia. The underlying condition should be treated such as administering antidepressants or electroconvulsive therapy to depressed patients or antipsychotic medications to schizophrenic patients. Patients who have suffered brain injury due to

GALE ENCYCLOPEDIA OF NEUROLOGICAL DISORDERS

1

Acetazolamide

stroke, bleeding, or trauma will benefit from rehabilitation programs that provide stimulation and attempt to re-teach skills. Research has looked at the possibility of treating abulia with medications that boost the activity of dopamine throughout the brain, but this is far from becoming a standard treatment.

Prognosis The prognosis of abulia depends on the prognosis of the underlying condition. Resources

Purpose Acetazolamide is used to treat a number of disorders, including the control of epileptic seizures in those individuals who suffer epilepsy. Acetazolamide is also used to treat non-neurological disorders such as glaucoma (acetazolamide decreases pressure in the eye), and to reduce the symptoms of edema (an excess storage of water by the body that leads to localized swelling or puffiness) and altitude sickness.

Description

BOOKS

Friedman, Joseph H. “Mood, Emotion, and Thought.” In Textbook of Clinical Neurology, edited by Christopher G. Goetz. Philadelphia: W. B. Saunders Company, 2003. PERIODICALS

Al-Adawi, Samir. “Abulia: The Pathology of ‘Will’ and Dopaminergic Dysfunction in Brain-Injured Patients.” Medical Sciences 1 (1999): 27–40. Nishie, M. “Posterior Encephalopathy Subsequent to Cyclosporin A Presenting as Irreversible Abulia.” Internal Medicine 42, no. 8 (1 August 2003): 750–755. Pantoni, L. “Abulia and Cognitive Impairment in Two Patients with Capsular Genu Infarct.” Acta Neurologica Scandinavia 104, no. 3 (1 September 2001): 185–190. Vijayaraghavan. “Abulia: A Delphi Survey of British Neurologists and Psychiatrists.” Movement Disorders 17, no. 5 (September 2002): 1052–1057.

Rosalyn Carson-DeWitt, MD

Acanthocytosis see Bassen-Kornzweig syndrome

Acetazolamide is prescription medication and is available only with a licensed physician’s prescription. Acetazolamide is available in oral form in extended release capsules and tablets. Acetazolamide can also be administered by injection.

Recommended dosage For both adults and children the recommended dosage for use in epilepsy cases is based upon actual body weight. In all cases, the exact dosage is determined by an experienced physician and/or pharmacist. In the most common cases, the normal recommended dosage is 4.5 mg per pound of body weight (10 mg per kg of body weight) and is administered in multiple (divided) doses delivered in the form of tablets or capsules. Doses must be taken on a regular schedule but individuals should not double dose to make up for a missed dose. When used to control anticonvulsive seizures, acetazolamide doses should not be stopped all at once. In most cases, physicians usually curtail (gradually lower) the dose an individual takes over time.

Precautions

❙ Acetazolamide Definition

Acetazolamide (a-set-a-ZOLE-a-mide) is a carbonic anhydrase inhibitor. Carbonic anhydrase is an enzyme that shifts the rate of reaction to favor the conversion of carbon dioxide and water into carbonic acid, bicarbonate ions, and free protons. Carbonic anhydrase activity is key to the regulation of pH and fluid balance in many different reactions throughout the body. Fluid buildup can alter the shape of the eye and cause pressure on the optic nerve. Clinically, this condition is described as glaucoma. Inhibition of the enzymatic work of carbonic anhydrase activity (e.g., through the action of a 2

carbonic anhydrase inhibitor) can lower fluid pressure in the eye.

As with most prescription medicines, acetazolamide should stored in a safe place—away from the reach of children. Acetazolamide should also be stored in a dry area away from excessive heat or light. Outdated medicine (medicines past their expiration date) should be discarded in a container that is safe from the reach of children. Women who are pregnant, plan to become pregnant, or who are breast-feeding infants should inform their physician of this fact before taking acetazolamide.

Side effects Unwanted side effects while taking acetazolamide include drowsiness, fatigue, or a dizzy lightheaded feeling. Individuals who experience these side effects should not

GALE ENCYCLOPEDIA OF NEUROLOGICAL DISORDERS

Key Terms Carbonic anhydrase An enzyme that shifts the rate of reaction to favor the conversion of carbon dioxide and water into carbonic acid, bicarbonate ions, and free protons.

Medline Plus. U.S. National Library of Medicine and the National Institutes of Health. (May 9, 2004). ORGANIZATIONS

National Eye Institute. 2020 Vision Place, Bethesda, MD 20892-3655. (301) 496-5248. .

Optic nerve The bundle of nerve fibers that carry visual messages from the retina to the brain.

Paul Arthur

operate machinery or drive while experiencing these symptoms. Other common side effects include shortness of breath. Acetazolamide can also lead to excessive depletion (loss) of potassium from the body. To counter this potential loss, many physicians recommend that patients eat food or drink beverages such as orange juice to replace lost potassium. The loss of potassium does not occur in every case, however, and high levels of potassium can also be dangerous. Individuals who show signs of potassium loss—including, but not limited to, dryness of mouth, increased thirst, or muscle cramps—should alert their physician. Because diet can impact a number of health factors, individuals should only alter their diet after consulting their physician. Individuals who are diabetic and who take acetazolamide may experience elevated sugar levels in their urine and blood. Individuals who experience changes in their vision should also consult their physician. In some rare cases, individuals may suffer depression, pains in the area of the kidneys, and bloody or black tarry stools.

Interactions Physicians and pharmacists are trained to evaluate the potential for adverse interactions by prescription drugs with other drugs. In the case of acetazolamide physicians evaluate potential adverse reactions with a range of drugs that include—but are not limited to—amphetamines, over-thecounter aspirins, cyclosporine, mood altering drugs (e.g., lithium), drugs used to control mental depression, drugs used to control irregular heartbeats, digoxin, diuretics (also known as water pills), and vitamins. Resources PERIODICALS

Varadkar S., J. S. Duncan, and H. Cross. “Acetazolamide and Autosomal Dominant Nocturnal Frontal Lobe Epilepsy.” Epilepsia 44 (July 2003): 986.

❙ Acupuncture Definition

Acupuncture, one of the main forms of therapy in traditional Chinese medicine (TCM), has been practiced for at least 2,500 years. In acupuncture, certain points on the body are stimulated by the insertion of fine needles. Unlike the hollow hypodermic needles used in mainstream medicine to give injections or to draw blood, acupuncture needles are solid. The points can be needled between 15° and 90° relative to the skin’s surface, depending on treatment. Acupuncture is thought to restore health by removing energy imbalances and blockages in the body. Practitioners of TCM believe that there is a vital force or energy called qi (pronounced “chee”) that flows through the body and between the skin surface and the internal organs, along channels or pathways called meridians. There are 12 major and eight minor meridians. Qi regulates the spiritual, emotional, mental, and physical harmony of the body by keeping the forces of yin and yang in balance. Yang is a principle of heat, activity, brightness, outwardness, while yin represents coldness, passivity, darkness, interiority, etc. TCM does not try to eliminate either yin or yang, but rather keep them in harmonious balance. Acupuncture may be used to raise or lower the level of yin or yang in a specific part of the body in order to restore the energy balance. Acupuncture was virtually unknown in the United States prior to President Richard Nixon’s trip to China in 1972. A reporter for the New York Times named James Reston wrote a story for the newspaper about the doctors in Beijing who used acupuncture to relieve his pain following abdominal surgery. By 1993, Americans were making 12 million visits per year to acupuncturists, and spending $500 million annually on acupuncture treatments. By 1995, there were an estimated 10,000 certified acupuncturists practicing in the United States; as of 2000, there were 20,000. About a third of the credentialed acupuncturists in the United States as of 2002 are MDs. Acupuncture’s record of success has stimulated a number of research projects investigating its mechanisms

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Acupuncture

OTHER

Acupuncture

Key Terms Cardiac tamponade A condition in which blood leaking into the membrane surrounding the heart puts pressure on the heart muscle, preventing complete filling of the heart’s chambers and normal heartbeat.

dried wormwood leaves, close to the skin to relieve pain. When used with acupuncture, the cone is placed on top of the needle at an acupuncture point and burned.

Electroacupuncture A variation of acupuncture in which the practitioner stimulates the traditional acupuncture points electronically.

Neurotransmitter A chemical in the brain that transmits messages between neurons, or nerve cells.

Endorphins A group of peptide compounds released by the body in response to stress or traumatic injury. Endorphins react with opiate receptors in the brain to reduce or relieve pain. Hyperemesis gravidarum Uncontrollable nausea and vomiting associated with pregnancy. Acupuncture appears to be an effective treatment for women with this condition. Meridians In traditional Chinese medicine, a network of pathways or channels that convey qi (also sometimes spelled “ki”), or vital energy, through the body. Moxibustion A technique in traditional Chinese medicine that involves burning a “Moxa,” or cone of

as well as its efficacy. Research has been funded not only by the National Center for Complementary and Alternative Medicine (NCCAM), but also by the National Institute on Alcohol Abuse and Alcoholism (NIAAA), the National Institute of Dental Research, the National Institute of Neurological Disorders and Stroke (NINDS), and the National Institute on Drug Abuse. In 1997, a consensus panel of the National Institutes of Health (NIH) presented a report in which it described acupuncture as a sufficiently promising form of treatment to merit further study. In 2000, the British Medical Association (BMA) recommended that acupuncture should be made more readily available through the National Health Service (NHS), and that family doctors should be trained in some of its techniques.

Pneumothorax A condition in which air or gas is present in the chest cavity. Qi The Chinese term for energy, life force, or vital force. Yin and yang In traditional Chinese medicine and philosophy, a pair of opposing forces whose harmonious balance in the body is necessary to good health.

used to treat a variety of disorders such as asthma, infertility, depression, anxiety, HIV infection, and fibromyalgia, although its efficacy in relieving these disorders is largely unproven. Acupuncture should not be used to treat traumatic injuries and other emergency conditions requiring immediate surgery. Also, while it appears to have benefits in relieving symptoms such as pain under the proper circumstances, it has not been shown to alter the underlying course of a disease. The exact mechanism by which acupuncture works is not known. Studies have demonstrated a variety of physiologic effects such as release in the brain of various chemicals and hormones, alteration of immune function, blood pressure, and body temperature.

Precautions

Purpose The purpose of acupuncture in TCM is the rebalancing of opposing energy forces in different parts of the body. In Western terms, acupuncture is used most commonly as an adjunctive treatment for the relief of chronic or acute pain. In the United States, acupuncture is most widely used to treat pain associated with musculoskeletal disorders, but it has also been used in the treatment of headaches, other painful disorders, and nausea and vomiting. In addition to these disorders, acupuncture has been 4

Opioids Substances that reduce pain and may induce sleep. Some opioids are endogenous, which means that they are produced within the human body. Other opioids are produced by plants or formulated synthetically in the laboratory.

The risk of infection in acupuncture is minimal if the acupuncturist uses sterile disposable needles. In the United States, the Food and Drug Administration (FDA) mandates the use of sterilized needles made from nontoxic materials. The needles must be clearly labeled as having their use restricted to qualified practitioners. Patients should also inquire about the practitioner’s credentials. People who would prefer to be treated by an MD or an osteopath can obtain a list of licensed physicians

GALE ENCYCLOPEDIA OF NEUROLOGICAL DISORDERS

Acupuncture

BL

ST LI

GV CV SI

KI

LU

HE

PE

TW

BL

GB SP

LV

Traditional Chinese medicine teachings state that channels of energy flow throughout the body, and that disease is caused by too much or too little flow of energy along these channels. Points along the channels, called meridians, are manipulated in acupuncture. In the illustration, points are shown on the bladder (BL), conception vessel (CV), gallbladder (GB), governing vessel (GV), heart (HE), kidney (KI), large intestine (LI), liver (LV), lung (LU), pericardium (PE), small intestine (SI), spleen (SP), stomach (ST), and triple warmer (TW) meridians. (Illustration by Electronic Illustrators Group.)

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Acupuncture

Governor vessel Bladder meridian Triple burner meridian

Conception vessel Stomach meridian Large intestine meridian

Small intestine meridian

Gallbladder meridian

Acupuncture sites and meridians on the face and neck. (Illustration by Hans & Cassady, Inc.)

who practice acupuncture in their area from the American Academy of Medical Acupuncture. With regard to nonphysician acupuncturists, 31 states have established training standards that acupuncturists must meet in order to be licensed in those states. In Great Britain, practitioners must qualify by passing a course offered by the British Acupuncture Accreditation Board. People seeking acupuncture treatment should provide the practitioner with the same information about their health conditions and other forms of treatment that they would give their primary care doctor. As is true with other forms of medical treatment, a minority of patients do not respond to acupuncture. The reasons for nonresponsiveness are not known at the present stage of research.

Description In traditional Chinese practice, the needles are twirled or rotated as they are inserted. Many patients feel nothing at all during this procedure, while others experience a prickling or aching sensation, and still others a feeling of warmth or heaviness.

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The practitioner may combine acupuncture with moxibustion to increase the effectiveness of the treatment. Moxibustion is a technique in which the acupuncturist lights a small piece of wormwood, called a moxa, above the acupuncture point above the skin. When the patient begins to feel the warmth from the burning herb, it is removed. Cupping is another technique that is a method of stimulation of acupuncture points by applying suction through a metal, wood, or glass jar, and in which a partial vacuum has been created. Cupping produces blood congestion at the site, and the site is thus stimulated. In addition to the traditional Chinese techniques of acupuncture, the following are also used in the United States: • Electroacupuncture. In this form of acupuncture, the traditional acupuncture points are stimulated by an electronic device instead of a needle. • Japanese meridian acupuncture. Japanese acupuncture uses thinner, smaller needles, and focuses on the meridians rather than on specific points along their course. • Korean hand acupuncture. Traditional Korean medicine regards the hand as a “map” of the entire body, such that

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• Western medical acupuncture. Western physicians trained in this style of acupuncture insert needles into socalled trigger points in sore muscles, as well as into the traditional points used in Chinese medicine. • Ear acupuncture. This technique regards the ear as having acupuncture points that correspond to other parts of the body. Ear acupuncture is often used to treat substance abuse and chronic pain syndromes. A standard acupuncture treatment takes between 45 minutes to an hour and costs between $40 and $100, although initial appointments often cost more. Chronic conditions usually require 10 treatment sessions, but acute conditions or minor illnesses may require only one or two visits. Follow-up visits are often scheduled for patients with chronic pain. As of 2000, about 70–80% of health insurers in the United States reimbursed patients for acupuncture treatments.

Preparation Apart from a medical history and physical examination, no specific preparation is required for an acupuncture treatment. In addition to using sterile needles, licensed acupuncturists will wipe the skin over each acupuncture point with an antiseptic solution before inserting the needle.

Aftercare No particular aftercare is required, as the needles should not draw blood when properly inserted. Many patients experience a feeling of relaxation or even a pleasant drowsiness after the treatment. Some patients report feeling energized.

Resources

Acupuncture

any part of the body can be treated by stimulating the corresponding point on the hand.

BOOKS

Pelletier, Kenneth R., MD. “Acupuncture: From the Yellow Emperor to Magnetic Resonance Imaging (MRI).” Chapter 5 in The Best Alternative Medicine. New York: Simon and Schuster, 2002. Reid, Daniel P. Chinese Herbal Medicine. Boston, MA: Shambhala, 1993. Svoboda, Robert, and Arnie Lade. Tao and Dharma: Chinese Medicine and Ayurveda. Twin Lakes, WI: Lotus Press, 1995. PERIODICALS

Cerrato, Paul L. “New Studies on Acupuncture and Emesis (Acupuncture for Relief of Nausea and Vomiting Caused by Chemotherapy).” Contemporary OB/GYN 46 (April 2001): 749. Kemper, Kathi J., et al. “On Pins and Needles—Pediatric Pain: Patients’ Experience with Acupuncture.” Pediatrics 105 (April 2000): 620–633. Kirchgatterer, Andreas. “Cardiac Tamponade Following Acupuncture.” Chest 117 (May 2000): 1510–1511. Nwabudike, Lawrence C., and Constantin IonescuTirgoviste. “Acupuncture in the Treatment of Diabetic Peripheral Neuropathy.” Diabetes 49 (May 2000): 628. Silvert, Mark. “Acupuncture Wins BMA Approval (British Medical Association).” British Medical Journal 321 (July 1, 2000): 637–639. Vickers, Andrew. “Acupuncture (ABC of Complementary Medicine).” British Medical Journal 319 (October 9, 1999): 704–708. ORGANIZATIONS

Risks Most complications from acupuncture fall into one of three categories: infections, most often from improperly sterilized needles; bruising or minor soft tissue injury; and injuries to muscle tissue. Rarely, serious side effects from improper application of the needle may result in pneumothorax and cardiac tamponade.

Normal results Normal results from acupuncture are relief of pain and/or improvement of the condition being treated.

Abnormal results

American Academy of Medical Acupuncture/Medical Acupuncture Research Organization. 5820 Wilshire Boulevard, Suite 500, Los Angeles, CA 90036. (800) 521-2262 or (323) 937-5514; Fax: (323) 937-0959. (May 9, 2004.) . American Association of Oriental Medicine. 433 Front Street, Catasaqua, PA 18032. (610) 266-1433; Fax: (610) 264-2768. (May 9, 2004.) . National Center for Complementary and Alternative Medicine (NCCAM) Clearinghouse. P.O. Box 7923, Gaithersburg, MD 20898. (888) 644-6226; TTY: (866) 464-3615; Fax: (866) 464-3616. (May 9, 2004.) .

Abnormal results from acupuncture include infection, a severe side effect, or worsening of the condition being treated.

GALE ENCYCLOPEDIA OF NEUROLOGICAL DISORDERS

Rebecca Frey, PhD Rosalyn Carson-DeWitt, MD

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Acute disseminated encephalomyelitis

❙ Acute disseminated

Key Terms

encephalomyelitis

Definition Acute disseminated encephalomyelitis (ADE) is a neurological disorder involving inflammation of the brain and spinal cord. A hallmark of the disorder is damage to the myelin sheath that surrounds the nerve fibers in the brain, which results in the inflammation.

Description Acute disseminating encephalomyelitis was first described in the mid-eighteenth century. The English physician who first described the disorder noted its association with people who had recently recovered from smallpox. Symptoms often develop without warning. As well, mental disorientation can occur. The disorder is also known as postinfectious encephalomyelitis and immune-mediated encephalomyelitis. The nerve demyelination that occurs in ADE also occurs in multiple sclerosis. However, the two maladies differ in that multiple sclerosis is long lasting and can recur over time, while ADE has a monophasic course, meaning that once it is over, further attacks rarely occur.

Demographics ADE can occur in both children and adults, although it occurs more commonly in children. ADE is not rare, accounting for approximately 30% of all cases of encephalitis (brain inflammation).

Causes and symptoms Acute disseminating encephalomyelitis can occur as a consequence of a bacterial or viral infection (including HIV), following recovery from infection with the malarial protozoan, or as a side effect of vaccination or another inoculation. ADE is usually a consequence of a viral illness, and occurs most often after measles, followed by rubella, chicken pox, Epstein-Barr, mumps and pertussis (whooping cough). Typically, symptoms appear two to three weeks after the precipitating infection or immunization. Alternatively, ADE may develop with no known associations. Despite the different causes, the symptoms that develop are similar. A number of non-specific symptoms, which vary from one person to another, include headache, stiff neck, fever, vomiting, and weight loss. These symptoms are quickly followed by lethargic behavior, seizures, hallucinations, sight difficulties, and even coma. Paralysis can occur in an arm or leg (monoparesis) or along an entire side of the body (hemiplegia). These symptoms can last a few weeks to a month. In some people, symptoms can progress from the appearance

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Encephalitis Inflammation of the brain, usually caused by a virus. The inflammation may interfere with normal brain function and cause seizures, sleepiness, confusion, personality changes, weakness in one or more parts of the body, and even coma. Myelin A fatty sheath surrounding nerves throughout the body that helps them conduct impulses more quickly.

of symptoms to coma and death in only a few days. Brain damage is largely confined to the white matter. Microscopic examination will typically reveal invasion of white blood cells into small veins. The nerve myelin damage occurs in the regions where the white blood cells accumulate. Examination of the brains of patients who have died of the disorder has not yielded consistent results. Some brains appear normal, while others display the nerve damage and white blood cell congestion.

Diagnosis Diagnosis is made based on the above symptoms and the patient’s medical history (i.e., recent infection or vaccination). In the early stages of the disorder, diagnosis can be confused with diseases including acute meningitis, acute viral encephalitis, and multiple sclerosis. Often, the latter can be ruled out using magnetic resonance imaging (MRI) and examination of the cerebrospinal fluid (CSF). Typically, in acute disseminating encephalomyelitis, CSF contains abnormally elevated levels of white blood cells and protein; and magnetic resonance imaging can reveal brain alterations.

Treatment team The treatment team typically consists of a primary care physician and, when hospitalization is necessary, nurses and specialized medical care personnel.

Treatment Corticosteroid medication is often prescribed in order to lessen the nerve inflammation. Use of high doses of steroids can often produce a rapid diminishing of the symptoms. Other kinds of treatment depend on the nature of the symptoms that develop. Supportive care includes keeping a patient comfortable and hydrated.

GALE ENCYCLOPEDIA OF NEUROLOGICAL DISORDERS

Persons recovering from acute disseminated encephalomyelitis need time to recover their normal consciousness and movements. Problems with memory, especially short-term memory, may be present. The recovering person sometimes has trouble controlling their emotions and is easily frustrated. Frequent periods of rest, alternating with shorter periods of mental and physical exercise are prescribed during initial recovery. The maximum possible recovery of brain and motor function may take a period of weeks or months.

Clinical trials There are no clinical trials for the study of ADE recruiting patients or being planned in the United States, as of January 2004. However, organizations such as the National Institute for Neurological Disorders and Stroke undertake and fund studies on disorders that involve damage to the myelin sheath of nerve cells. By understanding the nature of the disorders, it is hoped that detection can be improved and strategies will evolve to prevent or reverse the nerve damage.

Prognosis Prognosis varies from person to person. Some patients may recover fully, with no residual effects. Others may have some residual damage. Seldomly, ADE is fatal. Early detection and treatment improves a patient’s outlook.

Special concerns Although the incidence of ADE occurring after vaccination is rare, in recent years, public debate has led some parents to choose that their children not receive the recommended childhood vaccinations. The American Academy of Pediatrics asserts that, despite concerns about vaccine safety, vaccination is far safer than accepting the risks for the diseases that the vaccines prevent. Resources BOOKS

Icon Health Publications. The Official Patient’s Sourcebook on Acute Disseminated Encephalomyelitis: A Revised and Updated Directory for the Internet Age. San Diego: Icon Group International, 2002. PERIODICALS

Anlar, B., C. Basaran, G. Kose, A. Guven, S. Haspolat, A. Yakut, A. Serdaroglu, N. Senbil, H. Tan, E. Karaagaoglu, and K. Oguz. “Acute disseminated encephalomyelitis in children: outcome and prognosis.” Neuropediatrics (August 2003): 194–199. Brass, S. D., Z. Caramanos, C. Santos, M. E. Dilenge, Y. Lapierre, and B. Rosenblatt. “Multiple sclerosis vs

acute disseminated encephalomyelitis in childhood.” Pediatric Neurology (September 2003): 227–231. Koibuchi, T., T. Nakamura, T. Miura, T. Endo, H. Nakamura, T. Takahashi, H. S. Kim, Y. Wataya, K. Washizaki, K. Yoshikawa, and A. Iwamoto. “Acute disseminated encephalomyelitis following Plasmodium vivax malaria.” Journal of Infection and Chemotherapy (September 2003): 254–256. Narciso, P., S. Galgani, B. Del Grosso, M. De Marco, A. De Santis, P. Balestra, V. Ciapparoni, and V. Tozzi. “Acute disseminated encephalomyelitis as manifestation of primary HIV infection.” Neurology (November 2001): 1493–1496. OTHER

“Acute Disseminated Encephalomyelitis Information Page.” National Institute of Neurological Disorders and Stroke. (January 26, 2004). ORGANIZATIONS

National Institute for Neurological Diseases and Stroke (NINDS). 6001 Executive Boulevard, Bethesda, MD 20892. (301) 496-5751 or (800) 352-9424. . National Organization for Rare Disorders. 55 Kenosia Avenue, Danbury, CT 06813-1968. (203) 744-0100 or (800) 9996673; Fax: (203) 798-2291. .

Brian Douglas Hoyle, PhD

ADHD see Attention deficit hyperactivity disorder

❙ Adrenoleukodystrophy Definition

Adrenoleukodystrophy (ALD) is a progressive condition that affects both the adrenal glands (located atop the kidneys and responsible for the production of adrenalin) and myelin (the substance that insulates the nerves in the brain, spinal cord, and the limbs).

Description First described in the early 1900s, adrenoleukodystrophy was originally called Schilder-Addision disease. “Adreno” refers to the adrenal glands, “leuko” is the Greek word for white (myelin is the main component of the white matter in the brain and spinal cord), and “dystrophy” means impaired growth. This disease affects the adrenal glands and the growth of the myelin.

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Adrenoleukodystrophy

Recovery and rehabilitation

Adrenoleukodystrophy

Key Terms Adrenal insufficiency Problems with the adrenal glands that can be life threatening if not treated. Symptoms include sluggishness, weakness, weight loss, vomiting, darkening of the skin, and mental changes. Central nervous system (CNS) The CNS is composed of the brain, the cranial nerves, and the spinal cord. It is responsible for the coordination and control of all body activities. Leukodystrophy A disease that affects the white matter called myelin in the CNS. Myelin A fatty sheath surrounding nerves in the peripheral nervous system that helps them conduct impulses more quickly. Peroxisomes Tiny structures in the cells that break down fats so that the body can use them. Very long chain fatty acid (VLCFA) A type of fat that is normally broken down by the peroxisomes into other fats that can be used by the body.

Types of ALD There are three types of ALD, each with a different severity of symptoms and age of onset of ALD. All varying degrees of severity have been seen within the same family. Therefore, a family who has many mildly affected members could still have a more severely affected member. Some patients do not fall neatly into one of the three categories, and instead fall somewhere in between. Each type is given a different name, although all have mutations (changes in the genetic code) in the same gene and the same type of inheritance. The most severe form of ALD is called childhood ALD. About 35% of people with ALD have this type. These children usually have normal development in the first few years of life. Symptoms typically begin between four and eight years of age. Very rarely is the onset before the age of three or after the age of 15. In some boys, the first symptom may be seizures. Other children become hyperactive and have behavioral problems that may initially be diagnosed as attention deficit/hyperactivity disorder (ADHD). Early signs may also include poor school performance due to impaired vision that is not correctable by eyeglasses. Although these symptoms may last for a few months, other more severe problems develop. These include increasing problems with schoolwork and deterioration in handwriting and speech. Affected children usually develop clumsiness, difficulty in reading and comprehension of written material, aggressive or uninhibited 10

behavior, and various personality and behavioral changes. Most affected boys have problems with their adrenal glands by the time their first symptoms are noticed. A milder form of ALD, called adrenomyeloneuropathy (AMN), usually has a symptom onset at the age of 20 or later. Approximately 40–45% of people with ALD have AMN. The first symptoms are typically a progressive stiffness and weakness in the legs. Problems with urination and sexual function may also develop. Symptoms slowly progress over many years. Less than 20% of men with AMN will develop significant brain involvement that leads to cognitive and behavioral problems that are severe and may cause a shortened lifespan. About 70% of men with AMN will have problems with their adrenal glands when other symptoms are initially noticed. A third type of ALD is called Addison disease and affects about 10% of all of those with ALD. In this condition, people do not have the neurologic symptoms associated with ALD and AMN, but they do have problems resulting from adrenal insufficiency. Symptoms typically begin between two years of age and adulthood. The first symptoms are often vomiting, weakness, or coma. People with Addision disease may or may not have darker skin. Many who are initially diagnosed with Addison disease will later develop symptoms of AMN. In female carriers of ADL, about 20% will develop mild to moderate progressive stiffness and weakness in the legs and sometimes problems with urination. Rarely do they develop adrenal insufficiency. Symptoms in women generally do not begin before middle age.

Demographics ALD is found in all ethnic groups. About one in every 100,000 people suffers from ALD. Because the most severe form, called classic ALD, is X-linked, many more males than females are affected. Women are carriers of this X-linked form of the disease and may exhibit no or only mild symptoms. Another form of the disease is called neonatal ALD; this form of ALD is not X-linked and therefore both male and female babies exhibit symptoms. An adult-onset type of the disease is commonly called adrenomyeloneuropathy.

Causes and symptoms ALD causes problems in the peroxisomes, tiny cellular structures that are involved in breaking down large molecules of fats into smaller ones that can be used by the body. In ALD, the peroxisomes cannot break down a type of fat called very long chain fatty acid (VLCFA). As a result, VLCFAs accumulate throughout the body, particularly in the brain and adrenal glands. This accumulation interferes with the adrenal glands’ conversion of cholesterol into steroids, and prompts deterioration of the myelin

GALE ENCYCLOPEDIA OF NEUROLOGICAL DISORDERS

The adrenal glands of almost all individuals affected with ALD do not secret a sufficient amount of hormones; this is called adrenal insufficiency. Symptoms include sluggishness, weakness, weight loss, hypoglycemia, nausea, vomiting, darkening of the skin color, and mental changes. Because adrenal insufficiency can cause problems with regulating the balance of sodium and potassium in the body, a person can go into shock and coma, which can be potentially life threatening. As this aspect of ALD is readily treatable, identifying these patients helps prevent these complications.

Diagnosis When the diagnosis of ALD is suspected, the results of a test called magnetic resonance imaging (MRI) are sometimes abnormal. In this test, pictures of the brain are taken. In people with symptoms of ALD, there are usually detectable changes in the white matter. While an MRI can be helpful in making the diagnosis of ALD, a normal MRI does not exclude the diagnosis and an abnormal MRI does not definitively make the diagnosis of ALD. A more definitive diagnosis of ALD can be made by measuring the level of the VLCFA in the blood. In nearly all males with ALD, the level of the VLCFA in blood is very high. When ALD is suspected, testing should also be performed to measure the adrenal function. In 90% of boys with symptoms of ALD and 70% of men with AMN, the adrenal glands are affected. Approximately 85% of female carriers will have higher than normal levels of VLCFA in their blood. However, 15–20% of female carriers will have normal levels of VLCFA in their blood, which gives a “false negative” result. If a woman wants to be certain about her carrier status, genetic testing to look for a specific mutation in the ALD gene can be performed. Before a woman could have testing to determine her carrier status, a mutation in the ALD gene must have already been found in an affected member of the family.

effects; pediatric or adult endocrinologists to manage the adrenal complications; and pediatric or adult urologists to manage bladder complications in both children and adults and sexual problems in adults. In addition, physical therapists, occupational therapists, speech therapists, learning specialists, and behavioral psychologists may be helpful.

Treatment When the diagnosis of ALD is made, an important first step is to measure the level of adrenal function. If there is adrenal insufficiency, treatment should be given by steroid replacement, which can prove to be lifesaving. Adrenal function should be tested periodically. Lorenzo’s oil In the early 1990s, a film called Lorenzo’s Oil presented a fictionalized account of a real ALD patient, a young boy named Lorenzo, and his family’s search to find a cure for him. A possible treatment was found and was named Lorenzo’s oil. The Lorenzo’s oil therapy worked to reduce the level of VLCFA in the blood. The idea was that if the level of VLCFA could be reduced, perhaps it would cure or help the symptoms. After a number of years of use, Lorenzo’s oil unfortunately does not seem to be an effective treatment, at least in those with advanced signs and symptoms. Although it does reduce the level of VLCFA in blood, it does not seem to alter a person’s symptoms. Bone marrow transplant One promising treatment is bone marrow transplant. However, this is a potentially dangerous procedure that has a 10–20% rate of death. As of early 2001, information is available on a limited number of patients. In the very small number of patients who have had a bone marrow transplant, a few had their condition stabilize and a few even made slight improvements. However, all of these people had the bone marrow transplant at an early stage of their disease. This treatment does have drawbacks, including the fact that there are limited numbers of donors who are a suitable match and a significant risk that complications will develop from the transplant. Early data suggests that bone marrow transplant is most effective when it is performed at an early stage of the disease when neurological abnormalities are mild. Additional long-term studies are necessary to determine the overall success of these procedures.

Treatment team A number of professionals can provide supportive (though not curative) care for patients with adrenoleukodystrophy: neurogeneticists, to help with diagnosis; pediatric or adult neurologists (depending on the type of ALD and age of onset) to monitor and manage the neurological

Other treatments Research is being done with other treatments such as lovastatin and 4-phenylbutyrate, both of which may help lower VLCFA levels in cells, but more work is necessary to determine their effectiveness. Gene therapy, a possible

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Adrenoleukodystrophy

covering nerve cells within the white matter of the brain, thus interfering with nerve function. Additionally, fats that are usually made from the breakdown products of VLCFAs cannot be produced. Because these fats would usually be utilized in the synthesis of myelin, nerve function is further compromised.

Adrenoleukodystrophy

method of treatment, works by replacing, changing, or supplementing non-working genes. Although different gene therapy methods are being tested on animals, they are not ready for human trials. Other types of therapy and supportive care are of benefit to both affected boys and their families. Physical therapy can help reduce stiffness and occupational therapy can help make the home more accessible. Support from psychologists and other families who have been or are in a similar situation can be invaluable. Many men with AMN lead successful personal and professional lives and can benefit from vocational counseling and physical and occupational therapy. Prenatal diagnosis Prenatal testing to determine whether an unborn child is affected is possible if a specific ALD mutation has been identified in a family. This testing can be performed at 10–12 weeks gestation by a procedure called chorionic villus sampling (CVS), which involves removing a tiny piece of the placenta and examining the cells. It can also be done by amniocentesis after 14 weeks gestation by removing a small amount of the amniotic fluid surrounding the fetus and analyzing the cells in the fluid. Each of these procedures has a small risk of miscarriage associated with it. Couples interested in these options should have genetic counseling to carefully explore all of the benefits and limitations of these procedures. An experimental procedure, called preimplantation diagnosis, allows a couple to have a child that is unaffected with the genetic condition. This procedure is only possible for those families in which a mutation in the ALD gene has been identified.

Clinical Trials A number of clinical trials are underway, including testing the efficacy of Lorenzo’s oil (combination glyceryl trierucate and glyceryl trioleate), oral bile acid therapy with cholic acid, chenodeoxycholic acid, and ursodeoxycholic acid, and bone marrow or umbilical cord blood transplantation.

Prognosis The prognosis for people with ALD is highly variable. Those diagnosed with childhood ALD usually have a very rapid course. Symptoms typically progress very fast and these children usually become completely incapacitated and die within three to five years of the onset of symptoms. The symptoms of AMN progress slowly over decades. Most affected individuals have a normal lifespan. 12

Resources PERIODICALS

Laan, L. A. E. M., et al. “Childhood-onset Cerebral X-linked Adrenoleukodystrophy.” The Lancet 356 (November 4, 2000): 1608–1609. Moser, H. W., L. Bezman, S. E. Lu, and G. V. Raymond. “Therapy of X-linked Adrenoleukodystrophy: Prognosis Based Upon Age and MRI Abnormality and Plans for Placebo-controlled Trials.” Journal of Inherited Metabolic Disease 23 (2000): 273–277. Moser, H. W. “Treatment of X-linked Adrenoleukodystrophy with Lorenzo’s Oil.” Journal of Neurology, Neurosurgery and Psychiatry 67, no. 3 (September 1999): 279–280. Shapiro, E., et al. “Long-term Effect of Bone Marrow Transplantation for Childhood-onset Cerebral X-linked Adrenoleukodystrophy.” The Lancet 356, no. 9231 (August 26, 2000): 713–718. Suzuki, Y., et al. “Bone Marrow Transplantation for the Treatment of X-linked Adrenoleukodystrophy.” Journal of Inherited Metabolic Disease 23, no. 5 (July 2000): 453–458. Unterrainer, G., B. Molzer, S. Forss-Petter, and J. Berger. “Coexpression of Mutated and Normal Adrenoleukodystrophy Protein Reduces Protein Function: Implications for Gene Therapy of X-linked Adrenoleukodystrophy.” Human Molecular Genetics 9, no. 18 (2000): 2609–2616. Van Geel, B. M., et al, on behalf of the Dutch X-ALD/AMN Study Group. “Progression of Abnormalities in Adrenomyeloneuropathy and Neurologically Asymptomatic X-linked Adrenoleukodystrophy Despite Treatment with ‘Lorenzo’s Oil.’” Journal of Neurology, Neurosurgery and Psychiatry 67, no. 3 (September 1999): 290–299. Verrips, A., M. A. A. P. Willemsen, E. Rubio-Gozalbo, J. De Jong, and J. A. M. Smeitink. “Simvastatin and Plasma Very Long Chain Fatty Acids in X-linked Adrenoleukodystrophy.” Annals of Neurology 47, no. 4 (April 2000): 552–553. ORGANIZATIONS

National Organization for Rare Disorders (NORD). PO Box 8923, New Fairfield, CT 06812-8923. (203) 746-6518 or (800) 999-6673; Fax: (203) 746-6481. (May 9, 2004.) . United Leukodystrophy Foundation. 2304 Highland Dr., Sycamore, IL 60178. (815) 895-3211 or (800) 728-5483; Fax: (815) 895-2432. (May 9, 2004.) . WEBSITES

“Entry 300100: Adrenoleukodystrophy, (ALD).” OMIM— Online Mendelian Inheritance in Man. (May 9, 2004.) . Moser, Hugo W., Anne B. Moser, and Corinne D. Boehm. “X-linked Adrenoleukodystrophy.” March 9, 1999 (May 9, 2004). University of Washington, Seattle. GeneClinics.

GALE ENCYCLOPEDIA OF NEUROLOGICAL DISORDERS

Karen M. Krajewski, MS, CGC Rosalyn Carson-DeWitt, MD

❙ Affective disorders Definition

Affective disorders are psychiatric diseases with multiple aspects, including biological, behavioral, social, and psychological factors. Major depressive disorder, bipolar disorders, and anxiety disorders are the most common affective disorders. The effects of these disorders—such as difficulties in interpersonal relationships and an increased susceptibility to substance abuse—are major concerns for parents, teachers, physicians, and the community. Affective disorders can result in symptoms ranging from the mild and inconvenient to the severe and life-threatening; the latter account for more than 15% of deaths due to suicide among those with one of the disorders. Major depressive disorder (MDD), also known as monopolar depression or unipolar affective disorder, is a common, severe, and sometimes life-threatening psychiatric illness. MDD causes prolonged periods of emotional, mental, and physical exhaustion, with a considerable risk of self-destructive behavior and suicide. Major studies have identified MDD as one of the leading causes of work disability and premature death, representing an increasingly worldwide health and economic concern. Bipolar affective diseases are divided into various types according to the symptoms displayed: Type I (bipolar I, or BPI) and Type II (bipolar II or BPII) disease, cyclothymic disorder, and hypomania disorder. Other names for bipolar affective disease include manic-depressive disorder, cyclothymia, manic-depressive illness (MDI), and bipolar disorder. People with bipolar diseases experience periods of manic (hyper-excitable) episodes alternating with periods of deep depression. Bipolar disorders are chronic and recurrent affective diseases that may have degrees of severity, tending however to worsen with time if not treated. Severe crises can lead to suicidal attempts during depressive episodes or to physical violence against oneself or others during manic episodes. In many patients, however, episodes are mild and infrequent. Mixed states may also occur with elements of mania and depression simultaneously present. Some people with bipolar affective disorders show a rapid cycling between manic and depressive states. Anxiety disorders are also common psychiatric disorders, and are considered one of the most under-treated

Key Terms Anxiety disorder A psychiatric disorder involving the presence of anxiety that is so intense or so frequently present that it causes difficulty or distress for the individual. Bipolar disorder A psychiatric disorder marked by alternating episodes of mania and depression. Also called bipolar illness, manic-depressive illness. Depressive disorder A psychiatric disorder of varying degrees characterized by feelings of hopelessness, physical responses such as insomnia, and withdrawal from normal activities. Dysthymia A chronic mood disorder characterized by mild depression. Manic A period of excess mental activity, often accompanied by elevated mood and disorganized behavior. Phobia A persistent abnormal fear of an object, experience, or place.

and overlooked health problems. Among its common manifestations are panic syndromes, phobias, chronic generalized anxiety disorder, obsessive-compulsive disorder, and post-traumatic disorder. Anxiety disorders are important contributors to other diseases such as hypertension, digestive and eating disorders, and cardiac arrhythmia. Severe anxiety disorders often lead to tobacco addiction, alcohol abuse, and drug abuse.

Description People with major depressive disorder (MDD) experience periods of at least two weeks of symptoms that often include sadness, emotional heaviness, feelings of worthlessness, hopelessness, guilt, anguish, fear, loss of interest for normal daily activities, social withdrawal, inability to feel pleasure, physical apathy, difficulty in concentrating, and recurrent thoughts about death. Changes in sleeping pattern, with insomnia during the night and hypersomnia (excessive sleep) during the day, chronic fatigue, and a feeling of being physically drained and immobile may also occur. Irritability and mood swings may be present, and loss of appetite or overeating are common features. In severe cases, MDD may last for months, with those affected experiencing profound despair and spending most of their time isolated or prostrate in bed, considering or planning suicide. Approximately 50% of MDD patients attempt suicide at least once in their lives.

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Affective disorders

.

Affective disorders

In bipolar I disease (BPI), the manic episodes are severe, lasting from one week to three months or more if untreated, and often require hospitalization. Manic episodes are characterized by hyperactivity, feelings of grandiosity or omnipotence, euphoria, constant agitation, obsessive work or social activity, increased sexual drive, racing thoughts and surges of creativity, distractibility, compulsive shopping or money spending, and sharp mood swings and aggressive reactions, which may include physical violence against others. Depressive episodes may not occur in some BPI patients, but when present, the signs are similar to those of MDD and tend to last for months if untreated. In bipolar II disease (BPII), milder and fewer manic episodes occur than for those people suffering from BPI, and at least one major depressive episode is experienced. BPII depression is the most common form of bipolar disease. Depressive episodes are usually more frequent than manic episodes, and can also last for extended periods if untreated. Cyclothymia disorder is less severe, but tends to be chronic with frequent mood swings and single episodes lasting for at least two years. In some individuals, cyclothymic disorder is the precursor to a progressive bipolar disease. In others, the cyclothymic disorder remains chronic. Hypomania is a mild degree of mania, manifested as brief and mild episodes of inflated self-esteem and excitability, irritability, impatience, and demanding attitude. Those with hypomania often find it disturbing or impossible to relax or to remain idle. Feelings of urgency to work longer hours and accomplish several tasks simultaneously are common.

Demographics MDD is a leading cause of suicide, with more than 100,000 attempts per year in the United States alone. Affective disorders account for more than 200,000 suicide attempts in the United States, with an estimated mortality rate of 15%. Affective disorders are, however, a worldwide problem, and there are no racial differences, though Caucasian and Japanese males have been shown to be at higher risk of committing suicide. Suicide due to affective disorders is the second leading cause of mortality in teenagers in the United States and, among young adults, it accounts for 10–30% of deaths.

Causes and symptoms Cultural influences and social pressures in achievement-oriented societies are important risk factors in affective disorders symptoms. Wars, catastrophic events,

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severe economic recession, accidents, personal loss, and urban violence are other contributing or triggering factors. Alcohol and drug abuse have a direct impact on brain neurochemistry, as well as some diseases, medical interventions, and medications, constituting a risk factor as well. However, in most cases, alcoholism, tobacco use, and/or drug abuse are the clinical symptoms of an underlying affective disorder that is inherently predisposed to substance abuse. Adaptive neurochemical and structural brain changes occurring in childhood give rise to the symptoms of many affective disorders; the diseases tend to run in families, although specific genetic factors causing the diseases have not yet been identified. Malnutrition and nutritional deficiencies are also important triggering factors in many psychiatric and affective disorders, as well as brain contamination with toxic levels of heavy metals such as methyl-mercury, lead, and bismuth. The age of onset of bipolar diseases varies from childhood to middle adulthood, with a mean age of 21 years. MDD onset is highly variable, due to the presence of different possible factors such as family history, traumatic childhood, hormonal imbalance or seasonal changes, medical procedures, diseases, stress, menopause, emotional trauma and affective losses, or economical and social factors such as unemployment or social isolation. Children with one parent affected by MDD or bipolar disease are five to seven times more prone to develop some affective or other psychiatric disorder than the general population. Although an inherited genetic trait is also under suspicion, studies over the past 20 years, as well as ongoing research on brain development during childhood, suggest that many cases of affective disorder may be due to the impact of repetitive and prolonged exposure to stress on the developing brain. Children of bipolar or MDD parents, for instance, may experience neglect or abuse, or be required to cope in early childhood with the emotional outbursts and incoherent mood swings of adults. Many children of those with affective disorders feel guilty or responsible for the dysfunctional adult. Such early exposure to stress generates abnormal levels of toxic metabolites in the brain, which have been shown to be harmful to the neurochemistry of the developing brain during childhood. The neurochemical effects of stress alter both the quantities and the baseline systems of substances responsible for information processing between neurons such as neurotransmitters and hormones. Moreover, the stress metabolites such as glucocorticoids cause atrophy and death of neurons, a phenomenon known as neuronal crop, which alters the architecture of a child’s brain. Neurotransmitters have specific roles in mood and in behavioral, cognitive, and other physiological functions: serotonin modulates mood, satiety (satisfaction in appetite), and

GALE ENCYCLOPEDIA OF NEUROLOGICAL DISORDERS

Low levels of the neurotransmitters serotonin and norepinephrine were found in people with affective disorders, and even lower levels of serotonin are associated with suicide and compulsive or aggressive behavior. Depressive states with mood swings and surges of irritability also point to serotonin depletion. Lower levels of dopamine are related to both depression and aggressive behavior. Norepinephrine synthesis depends on dopamine, and its depletion leads to loss of motivation and apathy. GABA is an important mood regulator because it controls and inhibits chemical changes in the brain during stress. Depletion of GABA leads to phobias, panic attacks, chronic anxiety pervaded with dark thoughts about the dangers of accidents, hidden menaces, and feelings of imminent death. Acute and prolonged stress, as well as alcohol and drug abuse, leads to GABA depletion. Acetylcholine depletion causes attention and concentration deficits, memory reduction, and learning disorders. Chronic stress or highly traumatic experiences cause adaptive or compensatory changes in brain neurochemistry and physiology, in order to provide the individual with defense and survival mechanisms. However, such adaptive changes come with a high cost, in particular when they are required for an extended period such as in war zones, or other prolonged stressful situations. The adaptive chemicals tend to outlast the situation for which they were required, leading to some form of affective and behavioral disorder. These adaptive neurochemical changes are especially harmful during early childhood. For instance, neglected or physically, sexually, or emotionally abused children are exposed to harmful levels of glucocorticoids (comparable to those found in war veterans) that lead to neuron atrophy (wasting) and cropping (reduced numbers) in the hippocampus region of the brain. Neuronal atrophy and crop often cause cognitive and memory disorders, anxiety, and poor emotional control. Neuronal crop also occurs in the frontal cortex of the brain’s left hemisphere, leading to fewer nerve-cell connections with several other brain areas. These decreased nerve-cell connections favor

epilepsy-like short circuits or microseizures in the brain that occur in association with bursts of aggressiveness, self-destructive behavior, and cognitive or attention disorders. These alterations are also seen in the brains of adults who were abused or neglected during childhood. Time and recurrence of exposure and severity of suffered abuse help determine the extension of brain damage and the severity of psychiatric-related disorders in later stages of life.

Diagnosis Well-known sets of clinical characteristics associated with MDD, bipolar diseases, or anxiety disorders provide the physician the necessary data for an initial diagnosis of affective disorder. The psychiatrist analyzes the person’s pattern of mood, behavioral, and cognitive symptoms, along with the family history and environmental-contributing factors. Abnormal atrophy, or loss of volume, in the hippocampus and cortex areas of the brain are detectable on magnetic resonance imaging (MRI) and computed tomography (CT) scans. Postmortem neuropathological (brain tissue) analysis demonstrates reduced cells and/or neuron size reductions in several brain regions of those with affective disorders.

Treatment team The treatment team for people with affective disorders is primarily the psychiatrist, a medical doctor specializing in mood diseases and chemistry of the brain. Psychologists may also provide counseling and behavioral strategies for coping with the illness. Nurses administer prescribed medicine, along with monitoring behavior and physical condition during acute phases of the illness in the hospital setting. Mental health nurses also support treatment plans for clients in the community and provide a ready link to the psychiatrist. Additional community resources may include school psychologists, counselors, and support groups for affected people, as well as their family.

Treatment Psychotherapy alone is rarely sufficient for the treatment of affective disorders, as the existing neurochemical imbalance impairs the ability of a person with an affective disorder to respond. However, psychotherapy is important in helping to cope with guilt, low self-esteem, and inadequate behavioral patterns once the neurochemistry is stabilized and more normal levels of neurotransmitters are at work. Understanding of the devastating effects of stress in the brain of highly stressed or abused children made evident the need of medication as well as psychotherapy in

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Affective disorders

sleeping patterns; dopamine modulates reward-seeking behavior, pleasure, and maternal/paternal and altruistic feelings; norepinephrine determines levels of alertness, danger perception, and fight-or-flight responses; acetylcholine controls memory and cognition processes; gamma amino butyric acid (GABA) modulates levels of reflex/stimuli response and controls or inhibits neuron excitation; and glutamate promotes excitation of neurons. Orchestrated interaction of proper levels of different neurotransmitters is essential for normal brain development and function, greatly influencing affective (mood), cognitive, and behavioral responses to the environment.

Agenesis of the corpus callosum

early intervention. Administration of clonidine, a drug that inhibits the fight-or-flight response, and of other medications—or GABA supplementation—that interfere with levels of glucocorticoids in the brain can prevent both harmful neurochemical and architectural changes in the child’s central nervous system. Family and parental therapy is also crucial in order to reduce the presence of emotional stressors in the child’s life.

with affective disorders can expect to experience stabilization of their moods and anxiety, and can maintain an active role in work and social settings. Without treatment, daily activities and work are usually difficult to maintain within the cycles of mood disturbances, and social isolation, drug abuse, and suicide are often long-term consequences.

Teenagers and adults suffering from affective disorders may benefit from prescribed antidepressant medications that reduce symptoms. Recent studies have shown that antidepressants also encourage neuron cells in certain areas of the brain to mature, thus protecting the number of neurons in this area and preventing stress-induced neuronal crop. Lithium is beneficial to some bipolar and MDD patients, and also shows a protective effect against several neural injuries.

BOOKS

Antidepressants that inhibit the fast removal (i.e., reuptake) of serotonin from the receptors in neurons and that regulate norepinephrine concentrations in the neuronal networks of the brain are very effective in mood stabilization. After a few days of medication, symptoms often recede. Nutrient supplementation, especially with B-complex vitamins, GABA, and essential amino acids, optimizes the synthesis of neurotransmitters and important neuropeptides, which are important for balanced neurochemistry in the central nervous system.

Recovery and rehabilitation

DePaulo, Jr., J. Raymond, and Leslie Alan Horvitz. Understanding Depression: What We Know and What You Can Do about It. New York: John Wiley & Sons, Inc., 2002. Masters, Roger D., and Michael T. McGuire. The Neurotransmitter Revolution. Carbondale, IL: Southern Illinois University Press, 1994. Mondimore, Francis Mark. Bipolar Disorder: A Guide for Patients and Families. Baltimore: The Johns Hopkins University Press, 1999. PERIODICALS

Teicher, Martin H. “Wounds that Won’t Heal—The Neurobiology of Child Abuse.” Scientific American (March 2002): 68–75. Vogel, G. “Depression Drugs’ Powers May Rest on New Neurons.” Science 301, no. 757 (2003). OTHER

National Institute of Mental Health. For the Public. January 3, 2004 (March 30, 2004). . ORGANIZATIONS

Helping individuals with an affective disorder to recognize their particular symptoms and mood states is essential for recovery and rehabilitation. With recognition, a person may seek additional treatment during recurring episodes early enough to deter the harmful consequences of the disease.

Clinical trials As of early 2004, the National Institute of Mental Health (NIMH) is offering several clinical trials for adults and children with many types of affective disorders. People may participate at the institute’s main facility in Bethesda, Maryland, or at several locations throughout the United States. Further information and updates may be found at the NIMH clinical trials web site.

Prognosis

National Institute of Mental Health. 6001 Executive Boulevard, Room 8184, MSC 9663, Bethesda, MD 20892-9663. (301) 443-4513 or (866) 615-6464; Fax: (301) 443-4279. [email protected]. . Depression and Related Affective Disorders Association (DRADA). 2330 West Joppa Rd., Suite 100, Lutherville, MD 21093. (410) 583-2919. [email protected]. .

Sandra Galeotti

❙ Agenesis of the corpus callosum

Definition

Because affective disorders are usually long-term, cyclic conditions, ongoing treatment should be considered to prevent or modulate episodes of depression, mania, or severe anxiety. With preventative drug therapy, most people

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Resources

Agenesis of the corpus callosum (ACC) is an abnormality of brain structure, present at birth, that is characterized by partial or complete absence of the corpus callosum. The corpus callosum is a bundle of nerve fibers

GALE ENCYCLOPEDIA OF NEUROLOGICAL DISORDERS

Description Agenesis of the corpus callosum is one form of abnormal corpus callosum development. Other corpus callosum disorders include hypoplastic (thin or underdeveloped) corpus callosum and dysgenesis (abnormal formation) of the corpus callosum. In complete ACC, the corpus callosum is entirely missing. In partial ACC, some portion, usually the posterior portion, is absent. Agenesis of the corpus callosum is often found in combination with other brain abnormalities and some degree of mental impairment. Birth defects involving other parts of the body (especially the eyes, face, heart, and skeletal system) may also be present. ACC can occur alone, without other obvious brain abnormalities. In some of these cases, the affected person is healthy and has an IQ (intelligence quotient) in the normal range. Even in these cases however, subtle neuropsychological and cognitive abnormalities may exist.

Demographics Estimates of the frequency of ACC range between 0.0005% and 0.7% of children. An incidence of 2–3% has been reported in children with developmental disabilities. Between one-half to three-quarters of cases of ACC occur in males. ACC is a feature of Aicardi syndrome, an Xlinked (caused by a gene on the X chromosome) condition that occurs almost exclusively in females and is thought to be lethal in males.

Causes and symptoms The corpus callosum forms during the fifth to sixteenth week of pregnancy. It is thought that ACC occurs when one or more factors interfere with the migration (movement) of cells in the brain that eventually form the corpus callosum. An underlying cause for ACC is found in about one-half of cases. Factors that may affect normal corpus callosum development include: • prenatal infections, viruses, or toxic exposures such as rubella or fetal alcohol syndrome • chromosome abnormalities such as trisomy 8, trisomy 13, and trisomy 18 • genetic syndromes such as Aicardi syndrome, acrocallosal syndrome, Andermann syndrome, Shapiro syndrome, and Menkes disease • blocked growth of the corpus callosum due to cysts or other abnormal structures

• a cerebral dysgenesis syndrome, in which there is abnormal formation of the brain such as Dandy-Walker syndrome, Arnold-Chiari malformation, holoprosencephaly, or hydrocephalus The symptoms of ACC largely depend on the presence or absence of other medical conditions. The majority of children with ACC with other brain abnormalities usually show signs of a neurological disorder by age two. Symptoms in these children can include: • seizures • developmental delay or mental retardation • increased or decreased head size • hydrocephalus (abnormal accumulation of cerebrospinalfluid in the spaces of the brain) • cerebral palsy • hypotonia (decreased muscle tone) • failure to thrive In children with ACC who otherwise have limited neurological problems, there are slight differences in cognition (thought processes) and psychosocial functioning compared with children without ACC. Neuropsychological testing has shown that such individuals can have any of the following: • motor, language, or cognitive delays • poor motor coordination • sensitivity to tactile sensations • high pain tolerance • cognitive and social challenges Cognitive and social challenges may become more apparent with age. Examples of these challenges include difficulties using language in social settings and with performing tasks that require complex reasoning, creativity, or problem-solving skills. Patients with ACC may display limited insight into one’s own behavior, a lack of awareness of others’ feelings, misunderstanding of social cues, limited sophistication of humor, and difficulty imagining consequences of behavior.

Diagnosis A health professional suspicious of ACC may recommend a neurological evaluation that includes imaging studies. The more subtle cognitive and psychosocial problems found in individuals with isolated ACC are less likely to lead to the diagnosis. In some cases, the diagnosis of ACC is incidental, made in the course of an evaluation for other reasons. There may well be many asymptomatic individuals with partial or complete agenesis who never come to medical attention.

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Agenesis of the corpus callosum

that connects the two hemispheres (halves) of the brain and allows information to pass back and forth between both sides.

Agenesis of the corpus callosum

Suprapharyngeal ganglia (brain)

Mouth

Lateral nerve

Corpus callosum

Hypothalamus Thalamus

Diencephalon

Subpharyngeal ganglion

A. Earthworm brain Stomatogastric Deutocerebrum system Protocerebrum

Cerebrum Infundibulum Pituitary gland

Ventral nerve cord Tritocerebrum B. Insect brain

Cerebellum Midbrain Brain Pons Medulla stem oblongata

Thoracic ganglia Subesophageal ganglion

Spinal cord

Cerebral hemisphere

D. Human brain

Cerebellum Optic lobe C. Bird brain Diagram of the human brain (and others) with the corpus callosum indicated. (Illustration by Electronic Illustrators Group.)

Diagnosis of ACC relies on imaging studies such as ultrasound (prenatal or postnatal), magnetic resonance imaging (MRI), or computerized axial tomography (CT or CAT) scan. Diagnostic findings include: • absence of the corpus callosum • widely displaced and parallel lateral ventricles • selective dilatation of the posterior horns

Treatment team

• widely spaced frontal horns • upward displacement and enlargement of the third ventricle 18

• displaced orientation of gyral markings Fetal ultrasound can detect some but not all cases of ACC, beginning at about 20 weeks of pregnancy. The prenatal or postnatal diagnosis of ACC should be followed by studies aimed to determine the cause for the ACC. Such studies may include chromosome analysis, metabolic screening, and genetic and ophthalmologic consultations.

Treatment for patients with ACC is highly individualized because the severity of symptoms varies from patient to patient. Depending upon the symptoms, many

GALE ENCYCLOPEDIA OF NEUROLOGICAL DISORDERS

Arnold-Chiari malformation A condition in which the cerebellum, a structure in the brain, protrudes into the spinal canal. Cerebral palsy A brain injury that results in inability to use some muscles in the usual way. Chromosome Thin, rod-like fibers in the nucleus of a cell that contain the genes. Dandy-Walker syndrome A cyst in the cerebellum that involves the fourth ventricle (a space in the brain) and that may interfere with the body’s ability to drain cerebral spinal fluid. Failure to thrive Failure to grow and gain weight at the expected rate. Holoprosencephaly Brain, cranial, and facial malformations present at birth that are caused by incomplete cleavage of the brain during embryologic development. Hydrocephalus Abnormal accumulation of cerebrospinal fluid in the ventricles of the brain.

There are currently no clinical trials for patients with agenesis of the corpus callosum. Patients and families may elect to participate in genetic research. Laboratories searching for genes associated with agenesis of the corpus callosum include the laboratory of Elliott H. Sherr M.D., Ph.D, at the University of California, San Francisco, and the Harvard Institutes of Medicine. Both labs accept contact from patients and families.

Prognosis The prognosis for ACC varies according to the presence and severity of associated problems such as microcephaly (small head), seizures, cerebral palsy, and cerebral dysgenesis. In the case of a fetus diagnosed with isolated ACC, prediction of outcome remains imprecise. Estimates of the chance for a normal developmental outcome for a case detected prenatally range from 35–85%. It has also been stated that a so-called “normal” or “asymptomatic” outcome for ACC does not exist. Subtle or cognitive and psychosocial differences have been found in patients with ACC and a normal IQ.

Special concerns medical specialists can assist the patient’s primary physician or nurse practitioner, including a neurologist, ophthalmologist, geneticist, neuropsychologist, behavioral psychologist, occupational therapist, physical therapist, speech-language pathologist, and experts in special education and early intervention.

Treatment There is no cure for ACC. Treatment primarily includes management of associated problems such as seizures, hydrocephalus, and cerebral palsy.

Recovery and rehabilitation Limited information is available about the optimal remedial strategies for individuals with ACC. Speech therapy, occupational therapy, physical therapy, and early intervention are common services provided to patients with ACC. The goal of these therapies is to maximize the patient’s success in school, work, and life in general. Speech therapy can help patients with speech delays, apraxia (the inability to make voluntary movements despite normal muscle function), and difficulties with pragmatics or social language use. Occupational therapy can help patients with sensory integration problems. Physical therapy can help address problems such as impaired coordination, motor delays, and spasticity (abnormally increased muscle stiffness and restricted movement).

The special educational needs of children with ACC vary. Children with ACC may be eligible for an individual education plan (IEP). An IEP provides a framework from which administrators, teachers, and parents can meet the educational needs of a child with ACC. Depending upon severity of symptoms and the degree of learning difficulties, some children with ACC may be best served by special education classes or a private educational setting. Resources BOOKS

Brown, W. S., and M. T. Banich, eds. Development of the Corpus Callosum and Interhemispheric Interactions: A Special Issue of Developmental Neuropsychology. Mahwah, NJ: Lawrence Erlbaum Associates, Inc., 2001. Lassonde, M., and M. Jeeves, ed. Callosal Agenesis: A Natural Split Brain? New York: Plenum Press, 1994. Parker, James N., and Philip M. Parker, eds. The Official Parent’s Sourcebook on Agenesis of the Corpus Callosum: A Revised and Updated Directory for the Internet Age. San Diego: ICON Health Publications, 2002. Rourke, B. P., ed. Syndrome of Nonverbal Learning Disabilities: Neurodevelopmental Manifestations. New York: Guilford Press, 1995. PERIODICALS

Brown, W. S., and L. K. Paul. “Cognitive and Psychosocial Deficits in Agenesis of the Corpus Callosum with Normal

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Agenesis of the corpus callosum

Key Terms

Clinical trials

Agnosia

Key Terms Alzheimer’s disease A progressive, neurodegenerative disease characterized by loss of function and death of nerve cells in several areas of the brain, leading to loss of mental functions such as memory and learning. Formerly called presenile dementia. Anoxia Lack of oxygen. Asperger syndrome A developmental disorder of childhood characterized by autistic behavior but without the same difficulties acquiring language that children with autism have. Autism A syndrome characterized by a lack of responsiveness to other people or outside stimulus. Often occurs in conjunction with a severe impair-

Intelligence.” Cognitive Neuropsychiatry 5 (2000): 135–157. Davila-Gutierrez, G. “Agenesis and Dysgenesis of the Corpus Callosum.” Seminars in Pediatric Neurology 9 (December 2002): 292–301. Goodyear, P. W., C. M. Bannister, S. Russell, and S. Rimmer. “Outcome in Prenatally Diagnosed Fetal Agenesis of the Corpus Callosum.” Fetal Diagnosis and Therapy 16 (May–June 2001): 139–145. Shevell, M. I. “Clinical and Diagnostic Profile of Agenesis of the Corpus Callosum.” Journal of Child Neurology 17 (December 2002): 896–900. Stickles, J. L., G. L. Schilmoeller, and K. J. Schilmoeller. “A 23-Year Review of Communication Development in an Individual with Agenesis of the Corpus Callosum.” International Journal of Disability, Development and Education 49 (2002): 367–383. WEBSITES

The National Institute of Neurological Disorders and Stroke (NINDS). Agenesis of the Corpus Callosum Information Page. (March 30, 2004.) . Corpal Home Page. (March 30, 2004.) . National Center for Biotechnology Information. Online Mendelian Inheritance in Man (OMIM) Home Page. (March 30, 2004.) . ORGANIZATIONS

Agenesis of the Corpus Callosum (ACC) Network, 5749 Merrill Hall, Room 118, University of Maine, Orono, ME 04469-5749. (207) 581-3119; Fax: (207) 581-3120. [email protected]. Aicardi Syndrome Foundation. P.O. Box 3202, St. Charles, IA 60174. (800) 374-8518. [email protected]. .

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ment of verbal and non-verbal communication skills. Huntington’s disease A rare hereditary disease that causes progressive chorea (jerky muscle movements) and mental deterioration that ends in dementia. Huntington’s symptoms usually appear in patients in their 40s. Also called Huntington’s chorea. Parietal lobe One of two brain hemispheres responsible for associative processes. Temporal lobes A large lobe of each hemisphere of the brain that is located on the side of the head, nearest the ears. It contains a sensory area associated with hearing.

National Organization for Disorders of the Corpus Callosum (NODCC). 18032-C Lemon Drive PMB 363, Yorba Linda, CA 92886. (714) 717-0063. .

Dawn J. Cardeiro, MS, CGC

❙ Agnosia Definition

Agnosia is a neuropsychological disorder characterized by the inability to recognize common objects, persons, or sounds, in the absence of perceptual disability. There are three major types of agnosia: visual agnosia, auditory agnosia, and tactile agnosia. Agnosia is caused by lesions to the parietal and temporal lobes of the brain, regions involved in storing memories and associations of objects. The condition may arise following head trauma or stroke, or following carbon monoxide poisoning or anoxia.

Description Agnosia, from the Greek “not knowing,” describes a collection of disorders where the ability to recognize objects or sounds or retrieve information about them is impaired, in the absence of other perceptual difficulties, including memory, intellectual capabilities, and the capacity for communication. The disorder can affect visual, auditory or tactile object recognition, but visual agnosia is the most common form of the condition, and most often expressed as an inability to recognize people.

GALE ENCYCLOPEDIA OF NEUROLOGICAL DISORDERS

occur in a variety of neurological diseases, including Alzheimer’s and Huntington’s diseases, Asperger’s syndrome and autism, the term is best reserved for situations where impaired face recognition appears in absence of other neurological symptoms. Patients are often uncomfortable in social situations, although many learn to recognize people using other visual cues, such as hairstyles, glasses, or scars. Prosopagnosia can be diagnosed using the Warrington Memory Test for faces, or the Benton Face Recognition test. Although the latter will not indicate prosopagnosia, failing the test does help quantify the degree of impairment. Neuroimaging of the adult with prosopagnosia often reveals lesions in the lingual and fusiform gyri of the medial occipitotemporal cortex, which are frequently bilateral. Children who have acquired the condition in utero or genetically, however, may not show these cortical lesions. Auditory agnosia Auditory agnosics fail to ascribe values to verbal or non-verbal sounds. Individuals with pure word deafness have intact hearing, but are unable to understand the spoken word, typically the result of bilateral trauma to the temporal cortico-subcortical regions of the brain. Nonverbal auditory agnosics fail to associate sounds with specific objects or events, such as a dog’s bark or the slamming of a door. In these patients, the lesions tend to locate to the right hemisphere. Tactile agnosia Tactile agnosia, also called astereognosis, is often difficult to recognize as we rarely identify objects solely by feel. Information about the object, including its weight, size, and texture are not given any value. Lesions in the somatosensory cortex are thought to be responsible for the condition. Resources BOOKS

“Agnosia,” Section 14, Chapter 169. In The Merck Manual of Diagnosis and Therapy, Mark H. Beers, and Robert Berkow, eds. Whitehouse Station, NJ: Merck Research Laboratories, 1999. Farah, M. J. Disorders of Object Recognition and What They Tell us About Normal Vision, 2nd edition. Cambridge, MA: The MIT Press, 1995. Freinberg, T. E. and M. J. Farah. “Cognitive-Motor Disorders, Apraxias, and Agnosias.” In Neurology in Clinical Practice: Principles of Diagnosis and Management, 3rd edition, W. G. Bradley, R. B. Daroff, G. M. Fenichel, et al., eds. Boston, MA: Butterworth Heinemann, 2000.

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Agnosia

Visual Agnosia In addition to being the most common form of agnosia, visual agnosias are also the best understood. Lissauer was the first scientist to provide a detailed account of agnosia (1888). He hypothesized that disorders in visual object recognition could be classified as either apperceptive agnosia or associative agnosia. This classification continues to be used today although there is some debate as to whether the deficits occur as a dichotomy or as a spectrum. Apperceptive agnosics can see, but they lack higherlevel visual perception, which interferes with object information gathering. Apperceptive agnosics fail shaperecognition and shape-copying tests. In an attempt to copy a drawing of a circle, a patient with apperceptive agnosia my draw a series of concentric scribbles. Conversely, associative agnosics have normal perception, but fail to draw on stored memories or knowledge associated with the object, such as its name, or the way it feels when picked up. APPERCEPTIVE VISUAL AGNOSIA Carbon monoxide poisoning is a frequent cause of apperceptive visual agnosia. The ensuing brain damage is frequently profuse and located in the posterior region of the brain. Simultanagnosia, a syndrome related to apperceptive visual agnosia, describes a condition where scenes containing multiple objects cannot be interpreted as a whole. Instead patients with simultanagnosia, recognize only portions of the scene at one time, and fail to describe the overall nature of the scene and comprehend its meaning. Individuals capable of seeing only one object at a time are said to have dorsal simultanagnosia. The condition is associated with lesions in the posterior parietal cortex, which are frequently bilateral. Patients with ventral simultanagnosia retain the ability to recognize whole objects, but the rate of recognition is impaired. The left inferior temporo-occipital cortex is generally implicated in the deficit. ASSOCIATIVE VISUAL AGNOSIA Even when perception remains intact, some people have difficulty recognizing objects. For these people, who lack language or communication disorders or intellectual impairment, and who are able to create good copies of objects, the deficit lies in retrieving stored information about the object that would permit identification. However, many people can provide semantic information about the object without being able to provide the name. For example, the word “kangaroo” may remain elusive, but descriptors, such as “found in Australia” and “has a pouch” may be offered in its place. Many associative visual agnosics have difficulty recognizing faces (prosopagnosia) or words (pure alexia), others specific types of objects, such as tools, or animals. Prosopagnosia was first described by Quaglino and Borelli in 1867. Although deficits in face recognition

AIDS

PERIODICALS

Barton, J. J. S. “Disorders of face perception and recognition.” Neurologic Clinics of North America 21 (2003): 521–548. Hodgson, T. L., and C. Kennard. “Disorders of higher visual function and hemi-spatial neglect.” Current Opinion in Neurology 13 (2000): 7–12. Riddoch, M. J. and G. W. Humphreys. “Visual agnosia.” Neurologic Clinics of North America 21 (May 2003): 501–520. WEBSITES

National Institute of Neurological Disorders and Stroke (NINDS). NINDS Agnosia Information Page. .

Hemophiliac A person with the blood disorder hemophilia, an inherited deficiency in blood-clotting ability. Hemophiliacs require regular administration of blood products, and were especially at risk of acquiring AIDS from HIV-contaminated blood during the early years of the evolving AIDS epidemic, before tests were developed to identify the HIV virus in donated blood. Opportunistic infection An infection in a person with an impaired immune system caused by an organism that does not usually cause disease in people with healthy immune systems.

ORGANIZATIONS

Pandemic Widespread epidemic.

National Eye Institute (NEI), National Institutes of Health. Bldg. 31, Rm. 6A32, Bethesda, MD 20892-2510. (301) 496-52482 or (800) 869-2020. [email protected]. . National Institute on Deafness and Other Communication Disorders (NIDCD), National Institutes of Health. Bldg. 31, Rm. 3C35, Bethesda, MD 20892-2320, (301) 496-7243. [email protected]. . National Organization for Rare Disorders (NORD). P.O. Box 1968 (55 Kenosia Avenue), Danbury, CT 06813-1968. (203)744-0100 or (800) 999-NORD (6673); Fax: (203) 798-2291. [email protected]. .

Western blot A sensitive laboratory blood test for specific antibodies; useful in confirming the diagnosis of AIDS.

Description

Hannah M. Hoag, MSc

Aicardi syndrome see Agenesis of the corpus callosum

❙ AIDS

Definition Acquired immunodeficiency syndrome (AIDS) is the final and most serious stage of the disease caused by the human immunodeficiency virus. Symptoms begin when an HIV-positive person presents a CD4-cell (also called T cell, a type of immune cell) count below 200. AIDS happens concurrently with numerous opportunistic infections and tumors that are normally associated with the HIV infection. The most common neurological complications of AIDS involve opportunistic infections of the brain such as progressive multifocal leucoencephalopathy (PML) and meningitis, other opportunistic infections such as herpes zoster (shingles), peripheral neuropathy, depression, and AIDS-related dementia. 22

Key Terms

AIDS was first recognized in 1981 and has since become a major worldwide pandemic. Abundant evidence indicates that the human immunodeficiency virus (HIV), discovered in 1983, causes AIDS. By leading to the destruction and/or functional impairment of immune cells, notably CD4+ T cells, HIV progressively destroys the body’s ability to fight infections and to resist certain cancer formation. Before the HIV infection became widespread in the human population, AIDS-like syndromes occurred extremely rarely, and almost exclusively in individuals with known causes of immune suppression, such as those receiving chemotherapy or those with underlying cancers. A marked increase in unusual infections and tumors characteristic of severe immune suppression was first recognized in the early 1980s in homosexual men who had been otherwise healthy and had no recognized cause for immune suppression. An infectious cause of AIDS was suggested by geographic clustering of cases, a sexual link among cases, mother-to-infant transmission, and transmission by blood transfusion. Isolation of the HIV from patients with AIDS strongly suggested that this virus was the cause of AIDS. Since the early 1980s, HIV and AIDS have been repeatedly associated; the appearance of HIV in the blood supply has preceded or coincided with the occurrence of AIDS cases in every country and region where AIDS has been noted. Individuals of all ages from many risk groups, including homosexual men, infants born to HIV-infected

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HIV destroys CD4+ T cells, which are crucial to the normal function of the human immune system. In fact, depletion of CD4+ T cells in HIV-infected individuals is an extremely powerful predictor of the development of AIDS. Studies of thousands of individuals have revealed that most HIV-infected people carry the virus for years before enough damage is done to the immune system for AIDS to develop; however, with time, a near-perfect correlation has been found between infection and the subsequent development of AIDS.

Demographics In the United States, more than 733,000 people have AIDS, and an estimated one to two million people have HIV infection without the symptoms of AIDS. Internationally, since the AIDS epidemic began, more than 16 million deaths have been attributed to AIDS. The current estimate of worldwide disease prevalence is more than 33 million HIV infections. Ninety-five percent of these cases are in developing countries, generally in subSaharan Africa and Southeast Asia. Most HIV infections still occur in men; however, the frequency of infection in women is increasing, especially in developing countries. In the United States, fewer than 16% of all HIV cases are in women, whereas worldwide an estimated 46% of all HIV patients are women.

Causes and symptoms The cause of primary AIDS is infection with the HIV virus, transmitted via infected blood or body fluids. Methods of transmission of the virus include unprotected sex, especially anal intercourse; occupational needle stick or body fluid splash, which has an estimated transmission rate of less than 0.3%; sharing of needles in drug abuse; and receiving contaminated blood products. Opportunistic infections occur in individuals whose CD4 count is less than 200 cells/mm3 and those not taking preventative drugs. Symptoms of AIDS include: • cough and shortness of breath

• fever • vision loss • nausea, abdominal cramps, and vomiting • weight loss and extreme fatigue • severe headaches with neck stiffness Neurological complications of AIDS Almost 30% of people with AIDS develop peripheral neuropathy, causing tingling, numbness, and weakness in the arms and legs due to nerve damage. If severe, peripheral neuropathy can cause difficulty walking. Several drugs used to treat people with AIDS can contribute to the development of peripheral neuropathy. Several opportunistic infections experienced by people with AIDS involve the nervous system. Progressive multifocal leucoencephalopathy (PML) is a serious viral infection of the brain, most often caused by the JC virus. PML is fatal in more than 90% of cases within six months of diagnosis. Nearly 4% of people with AIDS, especially those with T-cell counts below 100, will develop the disease. Meningitis is an infection of the lining of the spinal cord and brain, and also occurs in some people with AIDS. Cryptococcus, a fungus that normally occurs in the soil and seldom affects persons with intact immune systems, can cause recurring meningitis in people with AIDS whose T-cell count is below 100. The common parasite Toxoplasma gondii often present in cat feces, raw meat, raw vegetables, and the soil can also cause encephalitis, or inflammation of the brain, in AIDS patients. Shingles is a painful nerve inflammation caused by a reactivation of the herpes varicella zoster virus, the same virus that causes chicken pox. Although not directly linked to HIV, shingles seems to occur more frequently in people with AIDS. Other neurological conditions associated with AIDS include depression, occurring at any time during the disease, and dementia, which sometimes occurs in the later stages of AIDS. Depression can stem from living with a chronic and progressive disease. AIDS-related dementia involves problems with thinking, memory, and usually also with controlling the arms and legs, and can stem from direct infection in the brain with the HIV virus. In the initial stages of the pandemic, almost 20% of persons with AIDS developed severe dementia. With the development of combination antiviral drugs, the rate of severe dementia in AIDS has been reduced by more than half. The number of persons with HIV and milder dementia has increased, however, as people with HIV live longer.

• seizures and lack of coordination • difficult or painful swallowing • confusion and forgetfulness • severe and persistent diarrhea

AIDS

mothers, heterosexual women and men, hemophiliacs, recipients of blood and blood products, health care workers and others occupationally exposed to HIV-tainted blood, and injection drug users have all developed AIDS with only one common denominator: HIV.

Diagnosis In the early stages of infection, HIV often causes no symptoms and the infection can be diagnosed only by testing a person’s blood. Two tests are available to diagnose

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AIDS

HIV infection, one that looks for the presence of antibodies produced by the body in response to HIV and the other that looks for the virus itself. Antibodies are proteins produced by the body whenever a disease threatens it. When the body is infected with HIV, it produces antibodies specific to HIV. The first test, called ELISA (enzyme-linked immunosorbent assay), looks for such antibodies in the blood. A positive ELISA has to be confirmed by another test called western blot or immunofluorescent assay (IFA). All positive tests by ELISA are not accurate and hence, western blot and repeated tests are necessary to confirm a person’s HIV status. A person infected with HIV is termed HIV positive or seropositive. Rapid tests that give results in five to 30 minutes are increasingly being used worldwide. The accuracy of rapid tests is stated to be as good as that of ELISA. Though rapid tests are more expensive, researchers have found them to be more cost effective in terms of the number of people covered and the time the tests take. The HIV antibodies generally do not reach detectable levels in the blood until about three months after infection. This period, from the time of infection until the blood is tested positive for antibodies, is called the window period. Sometimes, the antibodies might take up to six months to be detected. Even if the tests are negative, during the window period the amount of virus is very high in an infected person. If a person is newly infected, therefore, the risk of transmission is higher. Another test for HIV is called polymerase chain reaction (PCR), which looks for HIV itself in the blood. This test, which recognizes the presence of the virus’ genetic material in the blood, can detect the virus within a few days of infection. There are also tests like radio immuno precipitation assay (RIPA), a confirmatory blood test that may be used when antibody levels are difficult to detect or when western blot test results are uncertain.

Treatment team The treatment team often includes personal caregivers, physical therapists, dietitians, specialists (infectious disease specialists, dermatologists, nephrologists, ophthalmologists, pediatrists, psychiatrists, and neurologists), and social workers.

• Nonnucleoside reverse transcriptase inhibitors (NNRTIS): These medications are used in combination with other drugs to help keep the virus from multiplying. Examples of NNRTIS are delavirdine (Rescriptor) and nevirapine (Viramune). • Protease inhibitors: These medications interrupt virus replication at a later step in its lifecycle. These include ritonavir (Norvir), a lopinavir and ritonavir combination (Kaletra), saquinavir (Invirase), indinavir sulphate (Crixivan), amprenavir (Agenerase), and nelfinavir (Viracept). Using both classes of drugs reduces the chances of developing resistance in the virus. • Fusion inhibitors: This is the newest class of anti-HIV drugs. The first drug of this class (enfuvirtide [Fuzeon]) has recently been approved in the United States. Fusion inhibitors block HIV from entering the human immune cell. • A combination of several drugs called highly active antiretroviral therapy (HAART): This treatment is not a cure. The virus still persists in various body sites such as in the lymph glands. The antiretroviral drugs do not cure people of the HIV infection or AIDS. They stop viral replication and delay the development of AIDS. However, they may also have side effects that can be severe. These include decrease of red or white blood cells, inflammation of the pancreas, and painful nerve damage. Other complications are enlarged or fatty liver, which may result in liver failure and death.

Recovery and rehabilitation As there is no cure for AIDS, the focus is on maintaining optimum health, activity, and quality of life rather than on complete recovery. Occupational therapy can have a crucial role in assisting people living with HIV/AIDS to reengage with life, particularly through vocational rehabilitation programs. Occupational therapy can provide the patient with a series of learning experiences that will enable the individual to make appropriate vocational choices.

Clinical trials

Treatment Since the early 1990s, several drugs to fight both the HIV infection and its associated infections and cancers have become available, including: • Reverse transcriptase inhibitors: They interrupt the virus from making copies of itself. These drugs are AZT 24

(zidovudine [Retrovir]), ddC (zalcitabine [Hivid], dideoxyinosine), d4T (stavudine [Zerit]), and 3TC (lamivudine [Epivir]).

There are many ongoing clinical trials for AIDS. “HIV Vaccine Designed for HIV Infected Adults Taking Anti-HIV Drugs,” “When to Start Anti-HIV Drugs in Patients with Opportunistic Infections,” and “Outcomes of Anti-HIV Therapy during Early HIV Infection” are some trials that are currently recruiting patients at the National

GALE ENCYCLOPEDIA OF NEUROLOGICAL DISORDERS

Prognosis Presently, there is no cure for HIV infection or AIDS, nor is there a vaccine to prevent the HIV infection. However, there are new medications that help slow the progression of the infection and reduce the seriousness of HIV consequences in many people.

Special concerns The surest way to avoid AIDS is to abstain from sex, or to limit sex to one partner who also limits his or her sex in the same way (monogamy). Condoms are not 100% safe, but if used properly they will greatly reduce the risk of AIDS transmission. Also, avoiding the use of intravenous drugs (drug abuse, sharing contaminated syringes) is highly recommended. Resources BOOKS

Conner, R. F., L. P. Villarreal, and H. Y. Fan. AIDS: Science and Society. Sudbury, MA: Jones & Bartlett Publishers, 2004. Stine, G. J. AIDS Update 2004. Essex, England: Pearson Benjamin Cummings, 2003. PERIODICALS

Grant, A. D, and K. M. De Cock. “ABC of AIDS: HIV Infection and AIDS in the Developing World.” BMJ 322 (June 2001): 1475–1478. OTHER

“AIDS Factsheets.” AIDS.ORG. April 20, 2004 (May 27, 2004). . “How HIV Causes AIDS.” National Institute of Allergy and Infectious Disease. April 20, 2004 (May 27, 2004). . UNAIDS. The Joint United Nations Program on HIV/AIDS. April 20, 2004 (May 27, 2004). . ORGANIZATIONS

Centers for Disease Control (Office of Public Inquiries). Clifton Road, Atlanta, GA 30333. (800) 342-2437. . National Institute of Allergy and Infectious Disease. 6610 Rockledge Drive MSC 6612, Bethesda, MD 20892-6612. .

Greiciane Gaburro Paneto Brenda Wilmoth Lerner, RN Iuri Drumond Louro, MD, PhD

❙ Alcohol-related neurological disease

Definition Alcohol-related neurological disease represents a broad spectrum of conditions caused by acute or chronic alcohol intake.

Description Alcohol, or ethanol, is a poisonous chemical that has direct and toxic effects on nerve and muscle cells. The effects can be profound, and symptoms can include incoordination, weakness, seizures, memory loss, and sensory deficits. Alcohol has a profoundly negative effect on both the central nervous system (i.e., the brain and spinal cord) and the peripheral nervous system (i.e., nerves that send impulses to peripheral structures such as muscles and organs). Alcohol can have negative effects on neurological centers that regulate body temperature, sleep, and coordination. Alcohol can significantly lower body temperature. It disrupts normal sleep patterns because it decreases rapid eye movement (REM) during the dreaming stage of sleep. It also adversely affects muscle coordination, causing imbalance and staggering—alcohol is a toxic insult to the cerebellum, which is responsible for balance. Additionally, the chronic use of alcohol can cause a broad spectrum of abnormalities in mental functioning. Generally, persons exhibit poor attention, difficulty with abstraction and problem solving, difficulty learning new materials, reduced visuospatial abilities (capacity to discriminate between two-dimensional or three-dimensional space), and often require extra time to integrate visual information. Other related problems include thiamine deficiency (vitamin B-1) and liver disease (liver cirrhosis and possibly liver cancer).

Acute effects of alcohol When alcohol is ingested, it moves from the bloodstream into every part of the body that contains water, including the brain, lungs, kidneys, and heart. Alcohol distributes itself equally both inside and outside cells. Ninety-five percent of alcohol is eliminated from the body by breakdown in the liver, and 5% is eliminated through urine, sweat, and breath. Alcohol is broken down (metabolized) in the liver by a complex process called zero-order kinetics (broken down at a certain amount at a time). This means that alcohol is metabolized at a rate of 0.3 oz (8.8 ml) of pure ethanol per hour. Within moments after ingestion, alcohol reaches the brain and produces acute effects such as euphoria, sedation (calmness), anesthesia,

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Alcohol-related neurological disease

Institute of Allergy and Infectious Diseases (NIAID). Updated information on these and other trials for the study and treatment of AIDS can be found at the National Institutes of Health website for clinical trials at .

Alcohol-related neurological disease

Key Terms Cerebellum Part of the brain that is responsible for muscle control and maintenance of balance. Cortical atrophy A wasting away and decrease in size of the outer portion of the brain, or cerebral cortex. Diencephalon The relay station of the brain for impulses concerning sensation and movement. Euphoria An exaggerated state of psychological and physical well being. Gray matter Area deep in the brain that functions during thinking and contains nerve cells that have an insulation membrane called a myelin sheath. Incoordination Loss of voluntary muscle control resulting in irregular movements. Limbic system Part of the brain that functions in motivational and mood states.

to use one of the senses (e.g., eyesight or the sense of smell) or in the ability to learn using the senses (e.g., learning through the sense of touch). Damage to the diencephalon (major relay station for nerve signals moving within the brain, associated with memory functioning) occurs and is associated with chronic usage and malnutrition (a late-onset condition). The cerebral cortex (folded outer layer of the brain) is composed of nerve cells called gray matter, which functions as the center of intelligent behavior and higher consciousness. Neuroimaging studies reveal that there are definitive signs of morphological change such as cortical atrophy (a decrease in size of the cerebral cortex). Cortical atrophy induced by alcoholism is associated with deficits in spatial memory and visual associations, learning related to or caused by touch, and problem solving. Alcoholic subjects also exhibit a decrease in blood nourishing the frontal lobe (portion of the brain behind the forehead), whose functions include planning, carrying out, and monitoring goal-directed and socially acceptable behaviors.

Neurotransmitter deficits and the progression of alcoholism and a sleepy hypnotic state. Further effects include release of inhibitions and judgment, blunting of sexual desire, aggressiveness, and mood changes. Physical effects of intoxication (with continued consumption) include impairment of motor ability, muscle function, eyesight, reaction time, night vision, and depth perception. Continued consumption can be lethal because alcohol can depress heart and lung function, which can slow breathing and circulation. Lethality occurs when levels are high enough to paralyze breathing. However, death due to alcohol consumption is rare because body defenses tend to eliminate the chemical by vomiting or the person becomes comatose. Alcohol “hangovers” usually cause persons to have headache (due to dilation of blood vessels in the head), dehydration (alcohol acts as a diuretic increasing urine output), and upset stomach (due to irritation of stomach lining).

Specific neurological damage The effects of alcohol can include damage or impairment to brain systems and to specific regions in the brain. The limbic system, located deep inside the brain, has several functions, including memory. Long-term users of alcohol often exhibit memory loss due to damage of the limbic system structures called the amygdala and hippocampus, located in the temporal lobes. Damage to other parts of the limbic system can produce symptoms such as abnormalities in emotional functioning and in the ability

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Neurotransmitters are brain chemicals that allow nerve cells to communicate. These chemicals are released and picked up by specialized structures (receptors) in a space between nerve cells called a synapse. Alcohol can cause “up”-regulation or “down”-regulation effects on neurotransmitters. Over prolonged periods of alcohol abuse, the levels of receptors change. Genes that produce molecular copies of receptors may by turned off (decreasing activity) or on (increasing activity). Levels of glutamate (an amino acid that is an excitatory neurotransmitter in the brain) are abnormally altered. Glutamate is correlated with long-term potentiation (mechanism vital for learning and memory) in the brain. Even minute amounts of alcohol have profound effects on brain glutamate action. Interference with glutamate chemistry in the brain can cause memory impairment and may account for the short-lived condition called “blackouts.” Because alcohol suppresses the excitatory effect of glutamate on nerve cells, this can result in strokes and seizures. Another neurochemical that is altered due to chronic intake of alcohol is gamma-aminobutyric acid (GABA), a major inhibitory neurotransmitter in the brain. Initially, alcohol increases the effects of GABA, which produces a state of mild sedation. Over time with continued abuse, the GABA system is down regulated and, when alcohol is not present in the system, the inhibitory effects are lost and overexcitation of the brain results. Alcoholism is a chronic disease, with a natural history that progresses to death if the intake does not completely

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cramps, weakness, swelling, and tenderness in affected areas of muscle. Chronic alcoholic myopathy can be painless, but is associated with weakness due to nerve atrophy.

Demographics Alcoholism is a widespread and costly problem. Even though use has declined since 1981, two of three American adults drink alcoholic beverages. Approximately 6.5% to 10% of the total U.S. population are heavy drinkers and they consume 50% of all the alcohol ingested annually. Alcohol is heavily implicated in tragic events and is involved in 50% of all crimes, 50% of all fatal car accidents, 33% of all boat/aviation deaths and drowning, and 50% of all accidental death, suicides, and murder. Approximately 50% of alcoholics are not diagnosed, because alcoholics rarely admit to excessive consumption. In approximately 50% of Chinese, Japanese, and Koreans, an enzyme called aldehyde dehydrogenase is absent. This is the enzyme that breaks down alcohol in the liver. Thus in populations who do not have the enzyme, alcohol-related problems are less likely, because persons with this deficiency will become sick (face flushing, racing heart rate) when they consume alcohol. Persons who develop nerve damage as a result of chronic alcoholism have a greater mortality rate than the general population. Fetal alcohol syndrome is estimated to occur in 5.2 per 10,000 live births in the United States. Women are more likely to develop alcoholic myopathy more than men, because women can develop the complication with 40% less consumption than males.

Causes and symptoms Studies of adopted twins reveal that children of alcoholics have a greater propensity for alcoholism even though they were adopted away from the alcoholic parents. Additionally, research indicated that children of nonalcoholic parents are less likely to develop alcoholism even when adopted into families with an alcoholic parent(s). Adopted children of alcoholic parents have four times a greater risk of developing alcoholism than those born of nonalcoholic parents. The cause is ultimately a combination of genetic and environmental factors, and poor prevention programs among high-risk target populations.

Diagnosis Diagnosis of neurologic disease is based on clinical signs and symptoms. Psychometric testing, psychological evaluation, and appropriate medical tests (neuroimaging, blood chemistry, liver profiles, differential cell count) can help establish the diagnosis. Alcoholics can exhibit disorders in multiple organ systems, and careful, comprehensive examination is necessary in order to stage the disease

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Alcohol-related neurological disease

stop. The progress consists of three stages. During the beginning stage, the alcoholic becomes dependent on the mood-altering effects of alcohol. In the middle stage, drinking starts earlier and there is tolerance (when more alcohol is needed to produce effects); during this stage, alcohol consumption is out of control and alcoholics frequently exhibit denial. Heavy consumption causes symptoms of anxiety, depression, fatigue, anger, rage, lack of self-esteem, and self-loathing. Symptoms worsen as the disease progresses, and alcoholics develop hand tremors and shaking (delirium tremens) and morning hangover. The final stages of alcoholism progress to round-the-clock consumption despite extremely negative personal and social consequences. The disease progresses with symptoms of intense guilt and remorse (suppressed by more drinking), fear of crowds and public places, financial debt, legal problems, and ill health (including malnutrition). Late-stage disease typically involves liver degeneration (cirrhosis) and severe, even life-threatening, clinical signs (shakes and convulsions) during withdrawal without treatment. Insanity due to brain damage or death may occur during this stage. Alcohol can cause thiamine deficiency (vitamin B-1). The Wernicke-Korsakoff syndrome is a late complication due to vitamin B deficiency, resulting from malnutrition. These alcoholics have a condition called hepatic encephalopathy, caused by diminished capacity of the liver to metabolize and detoxify chemicals in the body. Symptoms of Wernicke-Korsakoff syndrome include agitation, confusion, and altered personality. There is peripheral neuropathy (damage to peripheral nerves), which is symmetrical and affects the lower extremities. If untreated, this syndrome can further cause brain (cerebellum) degeneration, abnormal gait (walking), memory deficits (retrograde amnesia), and difficulty with abstract thinking and the acquisition of new learning (anterograde amnesia). Even if successfully treated with vitamin therapy, patients may still have amnesia (a condition called Korsakoff Syndrome). Fetal alcohol syndrome is a condition that occurs in infants born to alcoholic mothers. Prenatal exposure to alcohol can impair and retard fetal development and growth. Affected infants have a characteristic appearance that consists of a flat nose, flat mid face, small head size, short stature, and a thin upper lip. Approximately 50% are mentally deficient and most others exhibit intellectual deficits. Affected babies typically suffer from poor coordination, decreased adipose (fat) tissue, cleft palate, attention deficit hyperactivity disorder (ADHD), decreased muscle tone, heart defects, eye/ear defects, and smaller jaw. Alcoholic myopathy (disorder affecting muscle tissue) can be either acute (rapid onset of symptoms) or chronic (slower onset to develop symptoms). Acute alcoholic myopathy can involve symptoms such as muscular

Alcohol-related neurological disease

and execute an effective interventional treatment plan. No single test can diagnose alcoholism. The diagnosis can be made once a careful evaluation of all the clinical data is available. Criminal information related to drunk driving can also help establish the diagnosis.

Treatment team The treatment for medical-related disorders can include a psychiatrist, neurologist, and members of an inpatient medical ward in a hospital or psychiatric unit. Professional psychotherapist services are necessary to initiate an interventional treatment program. Monitoring and follow-up care with primary care practitioners and specialists is part of a well-integrated treatment program.

Treatment Acute management of alcohol intoxication is supportive in nature, and patients are monitored and treated if heart or lung problems develop. Patients may require intravenous fluid replacement (due to fluid loss from sweating and fever). Agitation can be treated with medications called benzodiazepines. Wernickes’ syndrome can be reversed with IV thiamine replacement, and withdrawal seizures can be treated with antiepileptic medication. Damage to muscles (chronic alcoholic myopathy) can be treated by supplementation of deficient vitamins and special diets. This initial management of detoxification usually requires inpatient treatment ranging from three to 10 days. Patients must undergo intensive inpatient or outpatient psychotherapy, and a long process of recovery and rehabilitation.

Recovery and rehabilitation Involvement in nonprofessional community-centered support groups such as Alcoholics Anonymous (AA) that utilize the “12-step” recovery approach is helpful for maintaining sobriety. During early recovery, patients still exhibit mood swings and compulsions to drink. Patients should attempt to receive positive support from family and friends, take rest and good nutrition, and seek to share experiences with other alcoholics (e.g., through self-help groups). Patients should also receive professional psychotherapy treatment from a clinician with special certifications in addictions counseling, or from a specialist in forensic psychotherapy. Typical treatment using psychological techniques include cognitive behavioral therapy and motivational enhancement therapy.

Clinical trials Clinical trials are currently recruiting patients for government-sponsored medical research (National Institute on Alcohol Abuse and Alcoholics). Studies include the

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role of dopamine in response to alcohol, and the effects of another neurotransmitter, serotonin, in alcoholism.

Prognosis The prognosis depends on the motivation of the patient to stop drinking alcohol, and the extent of organ damage, which varies with each case. The prognosis can be favorable in some patients (with minimal organ damage) that successfully complete long-term intensive psychotherapy and stop drinking.

Special concerns Psychotherapy treatment may be long term and complicated. Frequently, there may be psychological problems that occur within families who have an alcoholic. Alcoholics may cause violence to or abuse of family members. Resources BOOKS

Goetz, Christopher G., et al., eds. Textbook of Clinical Neurology, 1st ed. Philadelphia: W. B. Saunders Company, 1999. Noble, John., et al., eds. Textbook of Primary Care Medicine, 3rd ed. St. Louis: Mosby, Inc., 2001. Rakel, Robert, A. Textbook of Family Practice, 6th ed. Philadelphia: W. B. Saunders Company, 2002. PERIODICALS

American Academy of Pediatrics. “Fetal Alcohol Syndrome and Alcohol-related Neurodevelopment Disorders (RD9948).” Pediatrics 106, no. 2 (August 2000). Finlayson, R. E., and R. D. Hurt. “Medical Consequences of Heavy Drinking by the Elderly.” Alcohol Problems and Aging (1998): 193–212. Fuller, R., and S. Hiller. “Alcoholism Treatment in the United States: An Overview.” Alcohol Research and Health 23, no. 2 (1999). Oscar-Berman, M., and C. Epstein. “Impairments of Brain and Behavior: The Neurological Effects of Alcohol.” Alcohol Health and Research World 21, no. 1 (1997). Vittadini, G., and G. Biscaldi. “Alcoholic Polyneuropathy: A Clinic and Epidemiological Study.” Alcohol and Alcoholism 36, no. 5 (2001). WEBSITES

National Institute on Alcohol Abuse and Alcoholism. (May 9, 2004). ORGANIZATIONS

Alcoholics Anonymous. Grand Central Station, P. O. Box 459, New York, NY 10163. . National Council on Alcoholism and Drug Dependence, Inc., 20 Exchange Place, Suite 2902, New York, NY 10005. (212) 269-7797 or (800) NCA-CALL; Fax: (212) 2697510. .

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Amniocentesis A procedure performed at 16-18 weeks of pregnancy in which a needle is inserted through a woman’s abdomen into her uterus to draw out a small sample of the amniotic fluid from around the baby for analysis. Either the fluid itself or cells from the fluid can be used for a variety of tests to obtain information about genetic disorders and other medical conditions in the fetus. Astrocytes Types of neuroglial cells in the central nervous system that help support other nerve cells. Chorionic villus sampling A medical procedure done during weeks 10-12 of a pregnancy. A needle is inserted into the placenta and a small amount of fetal tissue is withdrawn for analysis.

Laith Farid Gulli, MD Michael Mooney, MA, CAC

❙ Alexander disease Definition

Alexander disease (ALX) is a rare and often fatal nervous system disorder that primarily occurs in infants and children.

Description The main features of Alexander disease are progressive mental impairment and loss of motor control. Based on the age of onset and type of symptoms present, ALX has been classified into three forms: infantile, juvenile, and adult. Alexander disease is named for Dr. W. Stewart Alexander, an Australian pathologist who first described an infantile case in 1949. Since that time, 80% of cases described have also been the infantile form. About 14% of patients have the juvenile form, and adult cases are rare. All three forms of ALX are unified by the presence of Rosenthal fibers (RF), microscopic protein aggregates that are found in astrocytes in the brain and spinal cord. Though Rosenthal fibers are associated with other conditions, the numbers and distribution of RF-containing astrocytes are unique to Alexander disease. ALX is one of the leukodystrophies, a group of disorders characterized by imperfect formation or maintenance of white matter, the myelin

Chromosome A structure in the nucleus of a cell that contains a thread of DNA containing the genetic information (genes). Humans have 46 chromosomes in 23 pairs. DNA Deoxyribonucleic acid; the genetic material in cells that holds the inherited instructions for growth, development, and cellular functioning. Histologic Pertaining to histology, the study of cells and tissues at the microscopic level. Hydrocephalus An abnormal accumulation of cerebrospinal fluid within the brain. This accumulation can be harmful by pressing on and damaging brain structures. Quadriparesis Partial or incomplete paralysis of all four limbs.

sheath (insulation) that covers the nerves in the brain and spinal cord. Patients with ALX usually display loss of white matter, most prominently in the frontal lobes of the brain.

Demographics Alexander disease is thought to be quite rare with approximately 200 cases described. Although there are no known prevalence estimates, the disease has been reported in both males and females and in various ethnic and racial groups.

Causes and symptoms Most cases of Alexander disease are genetic, caused by a dominant mutation (change) in the glial fibrillary acidic protein (GFAP) gene on chromosome 17. Usually this mutation occurs randomly in an individual without a family history of the disease. There are reports of rare familial cases with affected siblings. Therefore, unaffected parents of a child with ALX are at a low risk to have another affected child. Individuals with ALX who live long enough to reproduce have a 50% chance for an affected child. Since GFAP mutations have not been found in all cases of ALX, there may rarely be other genetic or nongenetic explanations for this disease. The glial fibrillary acidic protein gene encodes a protein by the same name. GFAP helps to provide structural stability to the astrocytes, which are supporting cells in the brain similar to blood vessels. GFAP is found in Rosenthal fibers. Reports have suggested that GFAP gene mutations

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Alexander disease

Key Terms

Alexander disease

result in a toxic gain of function of the protein (GFAP) that leads to a minimal or absent production of myelin. As of 2003, the precise mechanisms by which GFAP mutations cause ALX were unresolved. In the infantile form of the disease, average age of onset is six months, with a range of birth to two years. Affected children tend to have progressive physical and mental retardation with loss of previously attained milestones. Head size becomes increasingly large and the forehead appears prominent as a result of megalencephaly (enlarged head and brain). Other disease manifestations include seizures, spasticity (stiffness of the arms and legs), quadriparesis, feeding problems, and ataxia (poor coordination). Hydrocephalus may also occur, especially in children with early onset of symptoms. The juvenile form of ALX usually presents between age four and the early teens. Patients may develop some or all of the following symptoms: speech problems, difficulty swallowing, frequent vomiting, spasticity of the legs, ataxia, gradual intellectual decline, seizures, megalencephaly, or breathing problems. White matter abnormalities in the juvenile form are less prominent than in the infantile form. The adult form of ALX represents the most variable and least common form of the disorder. Patients with the adult variant may have symptoms that mimic multiple sclerosis, or may display symptoms similar to the juvenile form of the disease, except with later onset and slower progression. White matter changes may or may not be present. Some adult cases have been discovered by chance when an autopsy reveals Rosenthal fibers, a characteristic finding of this disease.

Treatment team Management of ALX usually involves the services of multiple medical specialists. In addition to primary health care professionals, patients may require the care of specialists in neurology, neurosurgery, physical therapy, occupational therapy, social services, orthopedics, and gastroenterology. A genetic specialist, such as a clinical geneticist or a genetic counselor, may be helpful to the patient and family, especially at the time of diagnosis or prior to genetic testing. Families may also benefit from psychological counseling and contact with other families affected by ALX or another leukodystrophy.

Treatment There is no cure for Alexander disease. Treatment, which is symptomatic and supportive, primarily consists of attention to general care and nutritional needs, antibiotic therapy for infections, and management of associated complications such as anti-epileptic drug therapy for seizures. Surgical interventions, including placement of a feeding tube and/or shunting for hydrocephalus, may also be required. Orthopedic surgery for scoliosis has been reported in a case of Alexander disease.

Recovery and rehabilitation

Diagnosis A diagnosis of Alexander disease is usually based on radiologic findings and/or genetic test results in an individual who has symptoms suggestive of this condition. Radiologic studies that may aid in diagnosis include magnetic resonance imaging (MRI), a computerized tomography (CT) scan, or a head ultrasound. For example, an MRI of an individual with the infantile form typically reveals white matter loss that involves the frontal lobes of the brain, abnormalities of the basal ganglia and thalamus, and possibly, enlargement of the ventricles. Genetic testing is accomplished by looking for known or detectable mutations in the GFAP gene. In up to 94% of cases of ALX, a GFAP mutation is found. Prenatal diagnosis for couples with an affected child can be performed when the mutation responsible for ALX is known. The DNA of a fetus can be tested using cells obtained from chorionic villus sampling (CVS) or amniocentesis.

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Prior to the discovery of the gene responsible for the disease, diagnosis of ALX was made by demonstration of Rosenthal fibers in a biopsy or autopsy sample from the brain. Though genetic testing has largely replaced these histologic studies, a brain biopsy or autopsy may be indicated in select cases if the diagnosis cannot be made through other means.

Given the rarity of ALX, the potential for rehabilitation in this disorder is unknown. Depending upon the type, severity, and rate of progression of symptoms in a given individual, interventions such as physical, occupational, and speech therapy may be recommended for management of disease-related complications. In severe cases of ALX, consideration may be given to placement in a residential care facility that can provide 24-hour care and support services.

Clinical trials As of 2003, there were no clinical trials for patients with Alexander disease. As more is learned about how mutations in the GFAP gene cause disease, it is hoped that new therapies may be developed in the future. As of December 2003, two laboratories were conducting research on the GFAP gene; both accept contact from patients and

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Prognosis The course of Alexander disease is generally one of regression and progressive neurologic degeneration. Prognosis varies according to the form of the disease. Lifespan for patients with the infantile from is significantly reduced; affected individuals live anywhere from one to 10 years of age. For the juvenile form of the disease, survival ranges from several years after onset to the late teens, with rare cases living several decades. Due to the rarity of the adult form, little is known about the prognosis for this ALX variant. Resources BOOKS

Johnson, Anne B. “Alexander disease.” Chapter 34. In Handbook of Clinical Neurology, Vol 22 (66), edited by Hugo Moser. Amsterdam: Elsevier Press, 1996. PERIODICALS

Johnson, Anne B. “Alexander Disease: A Review and the Gene.” International Journal of Developmental Neuroscience 20 (June–August 2003): 391–394. Li, R., A. Messing, J. E. Goldman, and M. Brenner. “GFAP Mutations in Alexander Disease.” International Journal of Developmental Neuroscience 20 (June–August 2002): 259–268. Schiffmann, R., and O. Boespflug-Tanguay. “An Update on the Leukodystrophies.” Current Opinion in Neurology 14 (December 2001): 789–794. WEBSITES

The National Institute of Neurological Disorders and Stroke (NINDS). Alexander Disease Information Page. (February 18, 2004). . The Waisman Center. Alexander Disease Project. (February 18, 2004). . ORGANIZATIONS

National Organization for Rare Disorders. P.O. Box 1968, 55 Kensonia Avenue, Danbury, CT 06813. (203) 7440100 or (800) 999-NORD; Fax: (203) 798-2291. [email protected]. . United Leukodystrophy Foundation. 2304 Highland Drive, Sycamore, IL 60178. (815) 895-3211 or (800) 728-5483; Fax: (815) 895-2432. [email protected]. .

Dawn J. Cardeiro, MS, CGC

❙ Alpers’ disease Definition

Alpers’ disease is an early-onset, progressive neurological degenerative disease that severely affects the brain and liver. In the familial (inherited) form of the disorder, it is transmitted as a recessive condition, which means that parents are unaffected, but both are carriers. Carrier parents have a 25% risk of having their biological child affected with Alpers’ disease.

Description Alpers’ disease was first described by the late neurologist Alfons Maria Jakob (1884–1931). The disease was characterized and published by Bernard Jacob Alpers, Erna Christensen, and Knud Haraldsen Krabbe; thus, Alpers’ disease is also known as Christensen’s disease or Christensen-Krabbe disease. Additionally, the disease is known as progressive sclerosing poliodystrophy. Alpers’ disease afflicts children and is eventually fatal. Degeneration in cognitive processes (reasoning ability) and muscular involvement caused by the disease is unrelenting and relatively rapid. Physically, children with Alpers’ disease lose control of their muscle movements. The ramifications of this disorder can significantly affect the emotional state of the person with Alpers’ disease, along with family members caring for them.

Demographics Alpers’ disease is a rare disorder. Due to complications related to the diagnosis of Alpers’ disease, it is difficult to estimate how often it occurs in the population. Both genders are affected with equal frequency.

Causes and symptoms Children with Alpers’ disease usually develop symptoms between the ages of three months and five years old. Initially, the first symptom early in life is seizures (convulsions). These children tend to be hypotonic (unable to achieve normal muscle tone) and their limbs seem to be stiff. This is usually followed by the failure to reach cognitive and developmental milestones. Mental retardation is progressive in these children. Among the most devastating features of this disorder is the progressive dementia. In children with Alpers’ disease, mental deterioration can occur rapidly. The pathological nature of the defect involves an area of the brain called the cerebrum in which a specific part (the gray matter) is affected. Spastic quadriplegia (inability to use and control movements of the arms and legs) can develop in

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Alpers’ disease

families. They are the Children’s National Medical Center—Center for Genetic Medicine (202-884-6065 or ) and the University of Alabama at Birmingham, Michael Brenner Research Lab (608-263-9191 or ).

Alpers’ disease

Key Terms Hypotonia Decreased muscle tone. Mitochondrial DNA The genetic material found in mitochondria, the organelles that generate energy for the cell. Because reproduction is by cloning, mitochondrial DNA is usually passed along female lines. Spastic quadriplegia Inability to use and control movements of the arms and legs.

help affected families find local support organizations. There are also organizations such as the Genetic Alliance that help identify support groups to allow families affected by genetic diseases to find other families with the same or related disorders. These organizations can be a tremendous help in alleviating the many emotional and situational burdens that arise by allowing family members to talk to other families that have experience with diseases such as Alpers’ disease. Physical therapy can also be helpful to maintain range of motion in the child’s arms and legs for as long as possible.

Treatment the later stages of the disorder. Blindness is also observed, and this is usually due to a condition called optic atrophy. In optic atrophy, the optic nerve degenerates, resulting in the inability to process visual information from the eye to the brain. The liver is also affected. Liver conditions that these children experience are jaundice or complete liver failure in more severe cases. Researchers at the National Institutes of Health (NIH) consider that children with Alpers’ disease are often misdiagnosed as having childhood jaundice or liver failure. This is due to the problems associated with making a diagnosis in living patients. Currently, the specific mechanism, whether genetic, environmental, or both, that causes this disease is unknown. Scientists assume that Alpers’ disease is caused by an underlying metabolic defect. Mutations in the DNA of the mitochondria (DNA that is a separate genome from the nucleus) have been associated with this disorder. The mitochondria functions to produce energy to tissues and is particularly important for tissues such as the brain.

Diagnosis Currently, the only way to arrive at a definitive diagnosis is by autopsy following the death of the child. A postmortem examination of the brain and liver is required.

Treatment team Because children affected with Alpers’ disease usually develop convulsions, they are first directed to a neurologist. An experienced neurologist is always necessary in order to get the appropriate palliative (supportive) care and treatment for these seizures. As the disease progresses, occupational therapists can provide aids for positioning and comfort. Due to the rapid nature of the disorder and the unavailability of treatment to slow the progression, children with Alpers’ disease are usually unable to attend school. There are, however, support specialists and organizations that have experience with severe neurological disorders. The National Organization for Rare Disorder can 32

There is no cure for Alpers’ disease. Also, there is currently no treatment that will slow the progression of the disease. Therefore, treatment is aimed at symptoms such as the seizures. The neurologist must consider the choice of anticonvulsant carefully to avoid ones that may have an adverse effect on the liver.

Recovery and rehabilitation As Alpers’ disease is progressive and eventually fatal, emphasis is placed not upon recovery, but on maintaining functionality as long as possible. Several lifestyle adaptations must be addressed, as children with Alpers’ disease eventually require full-time personal care. Depending on how severely and how rapidly the symptoms develop, families may require structural changes such as wheelchair access or other household modifications.

Clinical trials As of February 2004, there are no ongoing clinical trials designed specifically to treat or study Alpers’ diseases.

Prognosis The prognosis for children with Alpers’ disease is poor. Affected individuals typically die within the first decade of life, but in some cases of rapid progression, death can occur in as little as a few months after symptoms become apparent. Seizures can be particularly devastating, as they are often continuous and can lead to death. Other causes of death include complications related to liver disease or cardio-respiratory failure. Resources PERIODICALS

Alpers, B. B. “Diffuse Progressive Degeneration of the Grey Matter of the Cerebrum.” Archives of Neurology and Psychiatry (1931) 25: 469–505. Blackwood, W., P. H. Buxton, J. N. Cumings, D. J. Robertson, and S. M. Tucker. “Diffuse Cerebral Degeneration in

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OTHER

National Institutes of Health (NIH). NINDS Alpers’ Disease Information Page. February 3, 2004 (March 30, 2004). . ORGANIZATIONS

Genetic Alliance, Inc. 4301 Connecticut Ave. NW, Suite 404, Washington, DC 20008-2369. (202) 966-5557; Fax: (202) 966-8553. [email protected]. . March of Dimes Birth Defects Foundation. 1275 Mamaroneck Avenue, White Plains, NY 10605. (914) 428-7100 or (888) MODIMES; Fax: (914) 428-8203. askus@ marchofdimes.com. . National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK). National Institutes of Health, Bldg. 31, Rm. 9A04, Bethesda, MD 20892-2560. (301) 4963583. . National Organization for Rare Disorders (NORD). P.O. Box 1968, 55 Kenosia Avenue, Danbury, CT 06813-1968. (203) 744-0100 or (800) 999-NORD; Fax: (203) 7982291. [email protected]. .

Bryan Richard Cobb, PhD

❙ Alternating hemiplegia Definition

Alternating hemiplegia is a very rare condition characterized by recurrent episodes of temporary paralysis.

Description Alternating hemiplegia usually begins affecting a child before the age of four. Bouts of recurrent, temporary paralysis may involve the arms, legs, facial muscles, and/or eye muscles. The manifestations may range from

Key Terms Dystonia Abnormal muscle movements and stiffening. Hemiplegia Paralysis on one side of the body. Migraine A type of chronic headache caused by a cascade of events in the brain, including initial dilatation or widening of blood vessels, followed by chemical release and then painful spasms of blood vessels in the brain. Paralysis Loss of ability to move a part of the body.

numbness or tingling in the affected body part to complete paralysis. The episodes last between minutes and days, and are usually resolved by sleep. A variety of other neurological problems may also be present in children with alternating hemiplegia. A less-severe variant of alternating hemiplegia is called “benign nocturnal alternating hemiplegia of childhood.” In this variant, a child awakens from sleep to a state of paralysis that resolves completely over 2–15 minutes. Children with this variant do not suffer from other associated neurological problems. This particular condition is thought to be a variant of a migraine headache.

Demographics Alternating hemiplegia is quite rare, with fewer than 100 diagnosed cases in the United States, and fewer than 240 diagnosed patients worldwide.

Causes and symptoms The underlying cause of alternating hemiplegia is unknown. Benign nocturnal alternating hemiplegia of childhood is thought to be a variant of migraine headache, and therefore may be caused by a similar mechanism (abnormal dilatation of blood vessels in the brain, followed by chemical release and then painful spasms of the blood vessels). Individual episodes seem to occur spontaneously, although in some individuals they may be precipitated by stress, sleep deprivation, or viral illness. Symptoms of alternating hemiplegia Episodes of alternating hemiplegia come on suddenly during wakefulness, and can last between hours and days. Either or both sides of the body may become numb, tingly, or completely paralyzed. Limbs may be limp or stiff (dystonic). Facial and eye muscles are often affected, as well as the limbs. Children with alternating hemiplegia also

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Alternating hemiplegia

Infancy (Alpers’ Disease).” Archives of Disease in Childhood 38, (1963): 193–204. Boyd, S. G., A. Harden, J. Egger, and G. Pampiglione. “Progressive Neuronal Degeneration of Childhood with Liver Disease (‘Alpers’ Disease’): Characteristic Neurophysiological Features.” Neuropediatrics 17, no. 2 (1986 May): 75–80. Christensen, E., and K. H. Krabbe. “Poliodystrophia Cerebri Progressiva (Infantilis): Report of a Case.” Archives of Neurology 61 (1949): 28–43. Fitzgerald, J. F., R. Troncone, and M. A. Del Rosario. “Clinical Quiz. Alpers’ Disease.” J Pediatr Gastroenterol Nutr. 28, no.5 (May 1999): 501, 509. Narkewicz, M. R., R. J. Sokol, B. Beckwith, J. Sondheimer, and A. Silverman. “Liver Involvement in Alpers’ Disease.” J Pediatr. 119, no.2, (Aug 1991): 260–7.

Alzheimer disease

usually experience progressive difficulty with balance and walking, excess sweating, mental impairment, developmental delay, problems with body temperature, shortness of breath, and seizures. Although sleep can ameliorate the symptoms, the symptoms may recur upon awakening. Symptoms of benign nocturnal alternating hemiplegia of childhood Symptoms of benign nocturnal alternating hemiplegia of childhood may begin when the child is about two years of age. Boys appear to be more frequently affected than girls. Episodes may be preceded by several days by headache, abnormal irritability, and oppositional behavior. The actual episodes commence when a child is asleep, causing the child to awaken suddenly, screaming or crying and drooling. Although the child may appear to be awake, he or she usually does not respond normally to questions or commands. Usually only one side of the body appears limp and paralyzed. The episodes usually last about fifteen minutes, end with the child falling back into sleep, and are completely resolved when the child awakens again. Some children experience headache and vomiting with each episode, further underscoring the proposed link with migraine headache. Although children with this condition do not seem to exhibit any permanent effects of their hemiplegic episodes, and generally have normal intelligence, there does appear to be an increased risk of hyperactivity, irritability, and oppositional defiant disorder in children who experience episodes of benign nocturnal alternating hemiplegia of childhood.

their duration and severity. Some researchers believe that decreasing the number and severity of attacks may improve the child’s overall cognitive prognosis, by preventing damage to the brain.

Prognosis The classic form of alternating hemiplegia has a poor prognosis, with progressively severe impairment of mobility and cognitive functioning, requiring long-term care. About half of all children with benign nocturnal alternating hemiplegia of childhood outgrow their episodes over time. Resources PERIODICALS

Chayes-Vischer, V. “Benign alternating hemiplegia of childhood: six patients and long-term follow-up.” Neurology 57, no. 8 (23 October 2001): 1491–1493. Grigg-Damberger, M. “Neurologic disorders masquerading as pediatric sleep problems.” Pediatric clinics of North America 51, no. 1 (1 February 2004): 89–115. Kavanaugh, M. “Benign alternating hemiplegia of childhood: new features and associations.” Neurology 62, no. 4 (24 February 2004): 672. WEBSITES

National Institute of Neurological Disorders and Stroke (NINDS). NINDS Alternating Hemiplegia Information Page. January 17, 2002. (June 3, 2004). . ORGANIZATIONS

Diagnosis There are no available tests to definitively diagnose either form of alternating hemiplegia. These disorders are diagnosed by ruling out other possible reasons for a child’s episodes and symptoms.

Alternating Hemiplegia of Childhood Foundation. Richard George, President. 11700 Merriman Road , Livonia, Michigan 48150. 888-557-5757. [email protected]. .

Rosalyn Carson-DeWitt, MD

Treatment team Children with the more benign form of alternating hemiplegia may not require an extensive treatment team, other than a neurologist to help in diagnosis. Children with the more severe form of alternating hemiplegia may require a neurologist, as well as other specialists to help with their progressive problems with walking, such as a physical and occupational therapist. Children with this disorder usually require a specialized educational setting.

Treatment There is no cure for either form of alternating hemiplegia. A drug called flunarizine has been used to treat the more severe type of alternating hemiplegia, in an effort to decrease the frequency of hemiplegic episodes, as well as 34

❙ Alzheimer disease Definition

Alzheimer disease is a neurological disorder characterized by slow, progressive memory loss due to a gradual loss of brain cells. Alzheimer disease significantly affects cognitive (thought) capabilities and, eventually, affected individuals become incapacitated. Alzheimer-related issues can cause emotional and financial upheaval for both the individuals with the disease and their families. Alzheimer disease is the most common form of dementia (loss of intellectual function) and, according to the National Institutes of Health (NIH), it is the fourth leading cause of death in adults.

GALE ENCYCLOPEDIA OF NEUROLOGICAL DISORDERS

Amyloid plaques A waxy protein substance that forms clumps in brain tissues, leading to brain cell death. Autosomal dominant disorder An inheritance pattern where an affected parent has a 50% chance of passing on a genetic mutation responsible for the disorder to their offspring in each pregnancy. Dementia Deterioration or loss of intellectual faculties, reasoning power, and memory due to organic brain disease. Neurofibrillary tangles An accumulation of twisted protein fragments inside nerve cells, and one of the characteristic structural abnormalities found in the brains of patients with Alzheimer disease.

Description The condition was first described in 1906 by Alois Alzheimer, a German physician. Alzheimer characterized two abnormal structures in the brain of a woman with dementia that are now considered the hallmarks of the disease: amyloid plaques and neurofibrillary tangles. The nature of Alzheimer disease is progressive. Initially, dementia is manifested by barely noticeable memory deficits. Eventually, the memory loss becomes more severe until it is incapacitating. Other symptoms such as confusion, the inability to articulate words correctly, and hallucinations occur with varying degrees. Emotional problems such as easy agitation, poor judgment, and feelings of withdrawal are also common in the early stages. Affected individuals are also likely to develop seizures, hypertonicity (increased muscle movements), and incontinence. Without treatment or supervision, death often results from malnutrition or pneumonia. From the initial symptoms, disease progression can last up to 25 years, although typically the duration ranges from eight to 10 years.

Demographics Dementia is thought to affect between 25–50% of individuals 85 years or older. The risk of developing Alzheimer disease increases with age and is independent of sex or geographical location (although there are environmental toxic agents that can impair various cognitive functions, including memory loss). A genetic association has been found for higher risk of developing Alzheimer disease in individuals with mutations in a particular gene who are also African American or Caribbean Hispanics.

Causes and symptoms Although there are several known causes of Alzheimer disease, about 75% of cases are sporadic and occur without a clear cause; this percentage represents people without a family history of the disorder. Scientists assume that these cases are due to a combination of unknown genetic predisposing factors and environmental exposures. Although various narcotics, therapeutic drugs, viruses, and toxins have been implicated in the etiology of the disease, there is currently no proof that they can cause Alzheimer disease. Genetic basis for Alzheimer disease Of all persons with Alzheimer disease, up to 25% of cases are thought to be part of a familial-based inheritance pattern and therefore are only determined based on family history or genetic test results. In general, these forms of Alzheimer disease are inherited as an autosomal dominant disorder, meaning that affected individuals have a 50% chance of passing on the mutated gene to their offspring in each pregnancy. There is a late-onset familial form (AD2), three early-onset familial forms (AD1, AD3, AD4), and a form of Alzheimer disease associated with Down syndrome. Down syndrome and Alzheimer disease Less than 1% of all cases of Alzheimer disease are due to a chromosomal defect called trisomy 21 (also known as Down syndrome). This occurs when there are three copies of genes found on chromosome 21, usually due to a person having an extra chromosome 21. These individuals usually develop Alzheimer disease after the age of 40. The APP gene, which encodes the amyloid precursor protein and is implicated in the pathogenesis of Alzheimer disease, is localized to chromosome 21; it is felt that people with Down syndrome overproduce this protein, resulting in its accumulation in the brain. The excess protein is thought to cause the disease. Early-onset familial Alzheimer disease A low percentage (2%) of Alzheimer cases results from a familial form of the disease in which there is an early onset of symptoms (AD1, AD3, and AD4), usually occurring before the age of 60. Age of onset usually occurs around 40–50 years, but can occur as early as 30 years.

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Alzheimer disease

Key Terms

This association is greatest in individuals with a positive family history of dementia. Approximately 10% of people 65 years or older are at risk for developing significant memory loss. More than half of these individuals (5% of all individuals 65 years or older) have Alzheimer disease. Approximately four in 10,000 individuals between the ages of 40 and 60 are at risk for having Alzheimer disease.

Alzheimer disease

The majority of these persons have family members that are also affected. The clinical manifestations are similar to the adult-onset form, with loss of memory and cognitive ability. In this form of Alzheimer disease, there are several chromosomal locations of genes implicated in causing the disease. AD1 accounts for approximately 10–15% of earlyonset Alzheimer disease and involves a protein called presenilin 1 that has a mutation in the gene that encodes it called PSEN1, which is found on chromosome 14. AD3 accounts for 20–70% of the early-onset familial form and is caused by mutations in APP found on chromosome 21, which encodes a protein called amyloid beta A4. AD4 is extremely rare and is caused by mutations in PSEN2, localized to chromosome 1, and encodes a protein called presenilin 2. Late-onset familial Alzheimer disease The late-onset familial form of Alzheimer disease (AD2) accounts for approximately 15–25% of all cases. These familial cases are seemingly indistinguishable from sporadic cases when observed clinically, but can be recognized based on molecular genetic testing. However, there is no clear chromosomal location for a gene directly responsible for the disease. Therefore, this complex type may involve many susceptibility genes. These familial cases are most likely due to multiple genes that make these individuals susceptible to developing the disease. For example, the APOE e4 gene on chromosome 19 associated with late-onset Alzheimer disease reduces the age in which symptoms develop by an unknown mechanism. There are many other candidate genes that are thought to modify Alzheimer disease risks and these genes, with various chromosomal locations, have been linked to the disease in different families. Development (pathogenesis) of Alzheimer disease Although scientists know how brain cells of persons with Alzheimer disease are affected, and additionally understand some of the genetic explanations of the disease, the precise cause of Alzheimer disease is still unclear. For example, it is known that accumulations of clumps of proteins called amyloid plaques outside brain cells and accumulation of altered proteins inside the cells called neurofibrillary tangles are characteristic of Alzheimer disease; however, it is unclear how these accumulated proteins cause brain cells to die. According to the Alzheimer’s Disease and Related Disorders Association, Inc., there are seven stages that characterize the disease: • Stage 1: No decline in function is yet noted. This group includes individuals who may carry predictive gene mutations but have no symptoms, or those who will be affected by other unknown mechanisms. 36

• Stage 2: Normal function in general, although the person is aware of a subtle cognitive decline. • Stage 3: Early Alzheimer disease. Persons experience difficulty in performing complex tasks that require cognitive skills. • Stage 4: Mild Alzheimer disease. Persons require assistance with common tasks such as paying bills and balancing a checkbook. • Stage 5: Moderate Alzheimer disease. Persons require assistance in making personal everyday decisions such as choosing appropriate clothing for the weather or ordering from a menu. • Stage 6: Moderately severe Alzheimer disease. Persons require assistance dressing, bathing, and using the toilet. Urinary and bowel incontinence may be present. • Stage 7: Severe Alzheimer disease. The vocabulary shrinks to only a few words; then little or no verbal communication is heard. The ability to walk is lost, followed by an inability to maintain a sitting posture in a chair. Eventually, the person experiences profound lack of purposeful muscle control, is totally dependent for care, and cannot smile or hold up his or her head.

Diagnosis Alzheimer disease is diagnosed clinically by a physician, postmortem by a histopathologist (a scientist who studies diseased tissues by their various staining patterns), or genetically by identifying mutations in genes associated with the disease. The gold standard for diagnosis of Alzheimer disease is through autopsy examination by an experienced pathologist. Detection of amyloid plaques in the brain by histopathology is the most conclusive diagnostic tool. This is performed using antibodies that bind to the particular amyloid proteins and can be visualized by microscopic evaluation, as the antibodies are tagged with a fluorescent or colorimetric molecule. A positive result would involve a significantly greater number of plaques compared to agematched controls. Other brain defects that characterize the disease, such as abnormal nerve cell configurations called intraneuronal neurofibrillary tangles, can also be detected by histopathology by the same methods. A clinical diagnosis by a physician accounts for 80–90% of patients diagnosed with Alzheimer disease. Clinical diagnosis A physician can use a number of different tests to assess memory skills, and, combined with any observed changes in the individual’s behavior, they can help make a diagnosis of Alzheimer disease. Other tests that are important in diagnosing the disorder can involve laboratory tests that require blood and urine or imaging studies of the

GALE ENCYCLOPEDIA OF NEUROLOGICAL DISORDERS

The score for these tests is numerical and relies heavily on a reference range determined by a patient’s age, sex, and the type of equipment used to perform the test. A positive result will only indicate that a patient is at high risk of having Alzheimer disease and requires further analysis for an accurate diagnosis. This test has yet to be widely performed and is, therefore, only available in certain reference laboratories.

Treatment team

The smaller, darker brain segment on the left is affected by Alzheimer disease; the segment on the right is from a healthy brain. (Simon Fraser/MRC Unit, Newcastle General Hospital/Science Photo Library. Reproduced by permission.)

brain. By using neuroimaging studies such as magnetic resonance imaging (MRI) scans, physicians have found that patients with Alzheimer disease often have diffuse atrophy (weakening or decrease in size) in a specific area of the brain called the cerebrum. Genetic diagnosis It has been shown that there is a significant association of a specific gene called APOE e4 with the development the early-onset form of the disease. There are three different types of Alzheimer disease that have been shown to be caused by mutations in three distinct genes known as APP, PSEN1, and PSEN2. However, determining the genotype (whether a patient carries this associated mutation) is not entirely conclusive. Currently, although APOE e4 mutation analysis can help in diagnosing a patient suspected of having Alzheimer disease, it is not used for predictive testing of these individuals.

Initially, a physician usually recommends counseling by a psychologist or a support group experienced with this disease. After the diagnosis, visits to the physician focus on treating mild behavioral changes such as depression. Eventually, treatment requires 24-hour supervision and nursing care. The caretakers are mostly nurses or professionals who are part of various assisted-living programs.

Treatment Pharmacological treatment Treatment of Alzheimer disease is mainly palliative (given for comfort) and focuses on mitigating symptoms. Each symptom is treated based on its severity and the other symptoms that are affecting the individual. Most affected individuals will eventually need professional care in assisted living or nursing homes. They require constant supervision as memory loss becomes incapacitating. There are several pharmacological interventions and treatment regimens that are suggested. Patients who have depression are treated with antidepressants. Tacrine is often prescribed to help with some of the behavioral problems and provides modest cognitive benefits in a small percentage of patients. Aricept, Galantamine, and Exelon are more recent drugs used for a similar purpose, and are not believed to cause liver toxicity; the liver must be monitored in those taking Tacrine. Non-steroidal anti-inflammatory drugs

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Alzheimer disease

Biochemical markers Although there are no tests to definitively diagnose Alzheimer disease, there are useful biochemical markers that can help distinguish Alzheimer disease from other disorders that involve dementia, including dementia caused by vascular disorders, drugs, or thyroid disease. Fluid that is found in the brain and spinal cord called cerebrospinal fluid can be tested for levels of two proteins, Tau and Aβ42, in patients that develop symptoms of dementia. Aβ42 accumulation in the brain is associated with reduced levels in the cerebrospinal fluid. Accumulation of the Tau protein in the brain is associated with Alzheimer disease. Therefore, increased Tau protein levels and decreased Aβ42 in the cerebrospinal fluid can pinpoint which persons have Alzheimer disease, regardless of the cause or the age of onset.

Alzheimer disease

(NSAIDs) are currently being investigated for their use in treating patients with Alzheimer disease. Coping with the disorder There are strategies to cope with this disorder and these should be considered in the beginning stages of the disease. Coping mechanisms depend on whether there are family members available for support. If an individual is without family members, relying on community support through neighbors or volunteers of Alzheimer disease organizations will be necessary. Many precautions can be made early on to avoid difficult or life-threatening situations later, while maintaining everyday activities in the home environment. Dealing with a person with Alzheimer disease with patience is important. Daily tasks should be performed when the person with Alzheimer disease feels best. Informing neighbors of the person’s condition is an important first step. Arranging for assistance, depending on the stage of the disorder, will become necessary. As the ability to drive may be compromised fairly early in the disorder, transportation may need to be arranged. There are local chapters of the Alzheimer’s Association that offer help with transportation requirements. In the early period of the disease when memory loss is minimal, it is helpful for family and friends to interact with the affected person, reminding him or her to take medication, eat, keep appointments, and so forth. Family and friends can help sustain the Alzheimer patient’s daily living activities. Keeping records is also helpful, particularly if several people are overseeing the patient’s care. Additionally, organizing the household so that it is easy to find important items is recommended. Other helpful coping mechanisms include posting signs to remind patients of important phone numbers, to turn off appliances, and to lock doors. It is important that all electrical cords and appliances are arranged to minimize distraction, and to prevent danger of falling or misuse. Assistance in handling finances is usually necessary. Providing an extra house key for neighbors and setting up a schedule to check on persons with Alzheimer disease is very helpful for both the patient and the family. By utilizing these and other family, neighborhood, and community resources, many people with early Alzheimer disease are able to maintain a successful lifestyle in their home environment for months or years.

Recovery and rehabilitation For a person with Alzheimer disease, emphasis is placed on maintaining cognitive and physical function for as long as possible. Currently, there is no cure for

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Alzheimer and, once the symptoms develop, patients do not recover. Instead, they progressively worsen, usually over a period of years. This has many psychosocial and financial ramifications for the patient and the patient’s caretakers. Social service workers can help families plan for long-term care, as persons with Alzheimer disease most often eventually require 24-hour assistance with feeding, toileting, bathing, personal safety, and social interaction. Taking care of patients in the later stages can be financially and psychologically draining. Various support systems are available through community mental health centers and national support organizations.

Clinical trials There are currently many clinical trials for the treatment or prevention of Alzheimer disease sponsored by the National Institutes of Health (NIH). Large multi-center clinical trials such as a Phase III clinical trail are aimed at determining whether anti-inflammatory drugs delay agerelated cognitive decline. (Contact information: UCLA Neuropsychiatric Institute, Los Angeles, California, 90024. Recruiter: Andrea Kaplan, (310) 825-0545 or her email: [email protected].) A Phase III clinical trial is also organized to test the drug Risperidone for the treatment of agitated behavior in Alzheimer’s patients. (Contact information: Palo Alto Veterans Administration Health Care System, Menlo Park, California, 94025. Recruiter: Erin L. Cassidy, PhD, (650) 493-5000, ext.27013 or her email: [email protected].) Other trials include: • A study on Valproate to prevent cognitive and behavioral symptoms in patients. Contact information: Laura Jakimovich, RN, MS, (585) 760-6578 or her email: [email protected]. • The drug Simvastatin, a cholesterol-lowering medication, is being studied to learn if it slows the progression of Alzheimer disease. Contact information: Stanford University, Palo Alto, California, 94304. Recruiter: Lisa M. Kinoshita, PhD, (650) 493-0571 or her email: [email protected]. • A study of the efficacy and dose of the drug NS 2330 to improve cognition. Contact information: Peter Glassman, MD, PhD, (800) 344-4095, ext. 4776 or his email: [email protected]. • A study of investigational medications for the treatment of Alzheimer patients. Contact information: Eli Lilly and Company, (877) 285-4559. There are also many other studies that are investigating various other pharmacological agents such as vitamin E and other currently available drugs.

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There is considerable variability in the rate of Alzheimer disease progression. The Alzheimer Disease Association claims that the time from the onset of clinical symptoms to death can range from three to 20 years, with an average duration of eight years. There are probably many environmental and genetic factors that play a role in the progression of the disease. The accumulation of damage and loss of brain cells eventually results in the failure of many different organ systems in the body. According to the National Institute of Neurological Disorders and Stroke, the most common cause of death is due to infection.

Special concerns Alzheimer disease should be distinguished from other forms of dementia. In some cases, depression can result in dementia-like symptoms. Other examples include chronic drug use, chronic infections of the central nervous system, thyroid disease, and vitamin deficiencies. These causes of dementia can often be treated. It is, therefore, important to obtain an accurate diagnosis to avoid complications associated with the inappropriate treatment and long-term care of these patients. There are also several genetically based syndromes in which dementia plays a role. Genetic counseling Genetic counseling is important for family members biologically related to patients with Alzheimer disease because each first-degree relative has as much as a 20% lifetime risk of also being affected. The risk to immediate relatives increases as more family members develop the disease. In the early-onset form of the disease, the inheritance pattern is thought to be autosomal dominant. This means that a carrier (who will eventually be affected) has a 50% chance of passing on the mutated gene to his or her offspring. The general consensus in the scientific and medical community is to not test children or adolescents in the absence of symptoms for adult-onset disorders. There are many problems associated with predictive testing of asymptomatic individuals who are not yet adults. Children who undergo predictive testing lose the choice later in life (when they are capable of understanding the full ramifications of the disease) to know or not to know this information. It is, therefore, an important consideration that involves ethical and psychological implications. Resources BOOKS

Franci, E. Daunwald, and K. J. Isrelbacher. New York: McGraw Hill, 2001. Castleman, Michael, et al. There’s Still a Person in There: The Complete Guide to Treating and Coping with Alzheimer’s. New York: Perigee Books, 2000. Mace, Nancy L., and Peter V. Rabins. The 36-Hour Day: A Family Guide to Caring for Persons with Alzheimer Disease, Related Dementing Illnesses, and Memory Loss in Later Life. New York: Warner Books, 2001. PERIODICALS

Campion, D., et al. “Early-onset Autosomal Dominant Alzheimer Disease: Prevalence, Genetic Heterogeneity, and Mutation Spectrum.” Am J Hum Genet 65 (1999): 664–70. Green, R.C. “Risk Assessment for Alzheimer’s Disease with Genetic Susceptibility Testing: Has the Moment Arrived?” Alzheimer’s Care Quarterly (2002): 3,208–14. Rogan, S., and C. F. Lippa. “Alzheimer’s Disease and Other Dementias: A Review.” Am J Alzheimers Dis Other Demen (2002) 17: 11–7. Romas, S. N., et al. “Familial Alzheimer Disease among Caribbean Hispanics: A Reexamination of Its Association with APOE.” Arch Neurol (2002) 59: 87–91. Rosenberg, R. N. “The Molecular and Genetic Basis of AD: The End of the Beginning: The 2000 Wartenberg Lecture.” Neurology 54 (2000): 2045–54. OTHER

ADEAR Alzheimer Disease Education and Referral Center. National Institute on Aging about Alzheimer’s Disease— General Information. February 10, 2004 (March 30, 2004). . National Institutes of Health. Alzheimer’s Disease. February 10, 2004 (March 30, 2004). . National Library of Medicine. Alzheimer’s Disease. MEDLINE plus Health Information. February 10, 2004 (March 30, 2004). . ORGANIZATIONS

Alzheimer’s Association. 919 North Michigan Avenue, Suite 1000, Chicago, IL 60611-1676. (312) 335-8700 or (800) 272-3900; Fax: (312) 335-1110. [email protected]. . Alzheimer’s Education and Referral Center. PO Box 8250, Silver Springs, MD 20907-8250. (800) 438-4380. [email protected]. . National Institute on Aging. Building 31, Room 5C27, 31 Center Drive, MSC 2292, Bethesda, MD 20892. (301) 496-1752. .

Bird, T. D. “Memory Loss and Dementia.” In Harrison’s Principles of Internal Medicine, 15th ed. Edited by A. S.

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Bryan Richard Cobb, PhD

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Prognosis

Amantadine

❙ Amantadine

Key Terms

Definition

Amantadine is a synthetic antiviral agent that also has strong antiparkinsonian properties. It is sold in the United States under the brand name Symmetrel, and is also available under its generic name.

Purpose Amantadine is used to treat a group of side effects, called parkinsonian side effects, that include tremors, difficulty walking, and slack muscle tone. These side effects may occur in patients who are taking antipsychotic medications used to treat mental disorders such as schizophrenia. An unrelated use of amantadine is in the treatment of viral infections of some strains of influenza A.

Description Some medicines, called antipsychotic drugs, that are used to treat schizophrenia and other mental disorders can cause side effects similar to the symptoms of Parkinson’s disease. The patient does not have Parkinson’s disease, but may experience shaking in muscles while at rest, difficulty with voluntary movements, and poor muscle tone. These symptoms are similar to the symptoms of Parkinson’s disease. One way to eliminate these undesirable side effects is to stop taking the antipsychotic medicine. Unfortunately, the symptoms of the original mental disorder usually come back; in most cases, simply stopping the antipsychotic medication is not a reasonable option. Some drugs such as amantadine that control the symptoms of Parkinson’s disease also control the parkinsonian side effects of antipsychotic medicines. Amantadine works by restoring the chemical balance between dopamine and acetylcholine, two neurotransmitter chemicals in the brain. Taking amantadine along with the antipsychotic medicine helps to control symptoms of the mental disorder, while reducing parkinsonian side effects. Amantadine is in the same family of drugs commonly known as anticholinergic drugs, including biperiden and trihexyphenidyl.

Recommended dosage Amantadine is available in 100 mg tablets and capsules, as well as a syrup containing 50 mg of amantadine in each teaspoonful. For the treatment of drug-induced parkinsonian side effects, amantadine is usually given in a dose of 100 mg orally twice a day. Some patients may need a total daily dose as high as 300 mg. Patients who are

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Acetylcholine A naturally occurring chemical in the body that transmits nerve impulses from cell to cell. It causes blood vessels to dilate, lowers blood pressure, and slows the heartbeat. Anticholinergic Related to the ability of a drug to block the nervous system chemical acetylcholine. Dopamine A chemical in brain tissue that serves to transmit nerve impulses (a neurotransmitter) and helps to regulate movement and emotions. Neurotransmitter A chemical in the brain that transmits messages between neurons, or nerve cells. Parkinsonian Related to symptoms associated with Parkinson’s disease, a nervous system disorder characterized by abnormal muscle movement of the tongue, face, and neck; inability to walk or move quickly; walking in a shuffling manner; restlessness; and/or tremors.

taking other antiparkinsonian drugs at the same time may require lower daily doses of amantadine (e.g., 100 mg daily). People with kidney disease or who are on hemodialysis must have their doses lowered. In these patients, doses may range from 100 mg daily to as little as 200 mg every seven days.

Precautions Amantadine increases the amount of the dopamine (a central nervous system stimulant) in the brain. Because of this, patients with a history of epilepsy or other seizure disorders should be carefully monitored while taking this drug. This is especially true in the elderly and in patients with kidney disease. Amantadine may cause visual disturbances and affect mental alertness and coordination. People should not operate dangerous machinery or motor vehicles while taking this drug.

Side effects Five to 10% of patients taking amantadine may experience nervous system side effects, including: • dizziness or lightheadedness • insomnia

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• impaired concentration

DeVane, C. Lindsay, PharmD. “Drug Therapy for Psychoses.” In Fundamentals of Monitoring Psychoactive Drug Therapy. Baltimore: Williams and Wilkins, 1990.

One to 5% of patients taking amantadine may experience other nervous system side effects, including: • irritability or agitation • depression

Jack Raber, PharmD

Ambenonium see Cholinergic stimulants

• confusion • lack of coordination

❙ Amnestic disorders

• sleepiness or nightmares • fatigue • headache In addition, up to 1% of patients may experience hallucinations, euphoria (excitement), extreme forgetfulness, aggressive behavior, personality changes, or seizures. Seizures are the most serious of all the side effects associated with amantadine. Gastrointestinal side effects may also occur in patients taking amantadine. Five to 10% of people taking this drug experience nausea and up to 5% have dry mouth, loss of appetite, constipation, and vomiting. In most situations, amantadine may be continued and these side effects treated symptomatically. One to 5% of patients taking amantadine have also reported a bluish coloring of their skin (usually on the legs) that is associated with enlargement of the blood vessels (livedo reticularis). This side effect usually appears within one month to one year of starting the drug and subsides within weeks to months after the drug is discontinued. People who think they may be experiencing this or other side effects from any medication should tell their physician.

Interactions Taking amantadine along with other drugs used to treat parkinsonian side effects may cause increased confusion or even hallucinations. The combination of amantadine and central nervous system stimulants (e.g., amphetamines or decongestants) may cause increased central nervous stimulation or increase the likelihood of seizures. Resources BOOKS

American Society of Health-System Pharmacists. AHFS Drug Information 2002. Bethesda: American Society of HealthSystem Pharmacists, 2002.

Definition

Amnestic disorders are conditions that cause memory loss.

Description Memory is the ability to retain and recall new information. Memory can be subdivided into short-term memory, which involves holding onto information for a minute or less, and long-term memory, which involves holding onto information for over a minute. Long-term memory can be further subdivided into recent memory, which involves new learning, and remote memory, which involves old information. In general, amnestic disorders more frequently involve deficits in new learning or recent memory. There are a number of terms that are crucial to the understanding of amnestic disorders. In order to retain information, an individual must be able to pay close enough attention to the information that is presented; this is referred to as registration. The process whereby memories are established is referred to as encoding or storage. Retaining information in the long-term memory requires passage of time during which memory is consolidated. When an individual’s memory is tested, retrieval is the process whereby the individual recalls the information from memory. Working memory is the ability to manipulate information from short-term memory in order to perform some function. Amnestic disorders may affect any or all of these necessary steps. The time period affecting memory is also described. Anterograde amnesia is more common. Anterograde amnesia begins at a certain point in time and continues to interfere with the establishment of memory from that point forward in time. Retrograde amnesia refers to a loss of memory for information that was learned prior to the onset of amnesia. Retrograde amnesia often occurs in conjunction with head injury, and may result in erasure of memory of events or information from some time period (ranging from seconds to months) prior to the head injury. Over the course of recovery and rehabilitation from a head

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Amnestic disorders

• nervousness or anxiety

Amnestic disorders

Key Terms Acetylcholine A brain chemical or neurotransmitter that carries information throughout the nervous system. Anterograde Memory loss for information/events occurring after the onset of the amnestic disorder. Delirium A condition characterized by waxingand-waning episodes of confusion and agitation. Dementia A chronic condition in which thinking and memory are progressively impaired. Other symptoms may also occur, including personality changes and depression. Retrograde Memory loss for information/events prior to the onset of the amnestic disorder. Transient ischemic attack (TIA) A stroke-like phenomenon in which a brief blockage of a brain blood vessel causes short-term neurological deficits that are completely resolved within 24 hours of their onset.

injury, memory may be restored or the period of amnesia may eventually shorten.

Demographics About 7% of all individuals over the age of 65 have some form of dementia that involves some degree of amnesia, as do about 50% of all individuals over the age of 85.

Causes and symptoms A number of brain disorders can result in amnestic disorders, including various types of dementia (such as Alzheimer’s disease), traumatic brain injury (such as concussion), stroke, accidents that involve oxygen deprivation to the brain or interruption of blood flow to the brain (such as ruptured aneurysms), encephalitis, tumors in the thalamus and/or hypothalamus, Wernicke-Korsakoff syndrome (a sequelae of thiamine deficiency usually due to severe alcoholism), and seizures. Psychological disorders can also cause a type of amnesia called “psychogenic amnesia.” A curious condition called transient global amnesia causes delirium (a period of waxing and waning confusion and agitation), anterograde amnesia, and retrograde amnesia for events and information from the several hours prior to the onset of the attack. Transient global amnesia usually only lasts for several hours. Ultimately, the individual recovers completely, with no lasting memory 42

Hippocampus

Amygdala

Memory loss may result from bilateral damage to the limbic system of the brain responsible for memory storage, processing, and recall. (Illustration by Electronic Illustrators Group.)

deficit. The cause of transient global amnesia is poorly understood; researchers are suspicious that it may be due to either seizure activity in the brain or a brief blockage in a brain blood vessel, which causes a brief stroke-like event that completely resolves without permanent sequelae (similar to a transient ischemic attack). Symptoms of amnestic disorders may include difficulty recalling remote events or information, and/or difficulty learning and then recalling new information. In some cases, the patient is fully aware of the memory impairment, and frustrated by it; in other cases, the patient may seem completely oblivious to the memory impairment or may even attempt to fill in the deficit in memory with confabulation. Depending on the underlying condition responsible for the amnesia, a number of other symptoms may be present as well.

Diagnosis Diagnosis of amnestic disorders begins by establishing an individual’s level of orientation to person, place, and time. Does he or she know who he or she is? Where he or she is? The day/date/time? An individual’s ability to recall common current events (who is the president?) may reveal information about the memory deficit. A family member or close friend may be an invaluable part of the examination, in order to provide some background information on the onset and progression of the memory loss,

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A variety of memory tests can be utilized to assess an individual’s ability to attend to information, utilize shortterm memory, and store and retrieve information from long-term memory. Both verbal and visual memory should be tested. Verbal memory can be tested by working with an individual to memorize word lists, then testing recall after a certain amount of time has elapsed. Similarly, visual memory can be tested by asking an individual to locate several objects that were hidden in a room in the individual’s presence. Depending on what types of conditions are being considered, other tests may include blood tests, neuroimaging (CT, MRI, or PET scans of the brain), cerebrospinal fluid testing, and EEG testing.

Treatment team A neurologist and/or psychiatrist may be involved in diagnosing and treating amnestic disorders. Depending on the underlying condition responsible for the memory deficit, other specialists may be involved as well. Occupational and speech and language therapists may be involved in rehabilitation programs for individuals who have amnestic disorders as part of their clinical picture.

remove the tumor. Individuals with transient global amnesia can be expected to fully recover from their memory impairment within hours or days of its onset. In the case of some traumatic brain injuries, the amnesia may improve with time (as brain swelling decreases, for example), but there may always remain some degree of amnesia for the events just prior to the moment of the injury. Resources BOOKS

Cummings, Jeffrey L. “Disorders of Cognition.” In Cecil Textbook of Internal Medicine, edited by Lee Goldman, et al. Philadelphia: W. B. Saunders Company, 2000. Gabrieli, John D., et al. “Memory.” In Textbook of Clinical Neurology, edited by Christopher G. Goetz. Philadelphia: W. B. Saunders Company, 2003. Mesulam, M.-Marsel. “Aphasias and Other Focal Cerebral Disorders.” In Harrison’s Principles of Internal Medicine, edited by Eugene Braunwald, et al. New York: McGrawHill Professional, 2001.

Rosalyn Carson-DeWitt, MD

Amphetamine see Central nervous system stimulants

Treatment In some cases, treatment of the underlying disorder may help improve the accompanying amnesia. In mild cases of amnesia, rehabilitation may involve teaching memory techniques and encouraging the use of memory tools, such as association techniques, lists, notes, calendars, timers, etc. Memory exercises may be helpful. Recent treatments for Alzheimer’s disease and other dementias have involved medications that interfere with the metabolism of the brain chemical (neurotransmitter) called acetylcholine, thus increasing the available quantity of acetylcholine. These drugs, such as donepezil and tacrine, seem to improve memory in patients with Alzheimer’s disease. Research studies are attempting to explore whether these drugs may also help amnestic disorders that stem from other underlying conditions.

Prognosis The prognosis is very dependent on the underlying condition that has caused the memory deficit, and on whether that condition has a tendency to progress or stabilize. Alzheimer’s disease, for example, is relentlessly progressive, and therefore the memory deficits that accompany this condition can be expected to worsen considerably over time. Individuals who have memory deficits due to a brain tumor may have their symptoms improve after surgery to

❙ Amyotrophic lateral sclerosis Definition

Amyotrophic lateral sclerosis (ALS) is a disease that breaks down tissues in the nervous system (a neurodegenerative disease) of unknown cause that affects the nerves responsible for movement. It is also known as motor neuron disease and Lou Gehrig’s disease, after the baseball player whose career it ended.

Description ALS is a disease of the motor neurons, those nerve cells reaching from the brain to the spinal cord (upper motor neurons) and the spinal cord to the peripheral nerves (lower motor neurons) that control muscle movement. In ALS, for unknown reasons, these neurons die, leading to a progressive loss of the ability to move virtually any of the muscles in the body. ALS affects “voluntary” muscles, those controlled by conscious thought, such as the arm, leg, and trunk muscles. ALS, in and of itself, does not affect sensation, thought processes, the heart muscle, or the “smooth” muscle of the digestive system, bladder, and other internal organs. Most people with ALS retain function of their eye muscles as well. However, various forms

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Amyotrophic lateral sclerosis

as well as information regarding the individual’s original level of functioning.

Amyotrophic lateral sclerosis

Key Terms Aspiration Inhalation of food or liquids into the lungs. Bulbar muscles Muscles of the mouth and throat responsible for speech and swallowing. Fasciculations Involuntary twitching of muscles. Motor neuron A nerve cell that controls a muscle. Riluzole (Rilutek) The first drug approved in the United States for the treatment of ALS. Voluntary muscle A muscle under conscious control; contrasted with smooth muscle and heart muscle, which are not under voluntary control.

of ALS may be associated with a loss of intellectual function (dementia) or sensory symptoms. “Amyotrophic” refers to the loss of muscle bulk, a cardinal sign of ALS. “Lateral” indicates one of the regions of the spinal cord affected, and “sclerosis” describes the hardened tissue that develops in place of healthy nerves. ALS affects approximately 30,000 people in the United States, with about 5,000 new cases each year. It usually begins between the ages of 40 and 70, although younger onset is possible. Men are slightly more likely to develop ALS than women. ALS progresses rapidly in most cases. It is fatal within three years for 50% of all people affected, and within five years for 80%. Ten percent of people with ALS live beyond eight years.

Causes and symptoms Causes The symptoms of ALS are caused by the death of motor neurons in the spinal cord and brain. Normally, these neurons convey electrical messages from the brain to the muscles to stimulate movement in the arms, legs, trunk, neck, and head. As motor neurons die, the muscles they enervate cannot be moved as effectively, and weakness results. In addition, lack of stimulation leads to muscle wasting, or loss of bulk. Involvement of the upper motor neurons causes spasms and increased tone in the limbs, and abnormal reflexes. Involvement of the lower motor neurons causes muscle wasting and twitching (fasciculations). Although many causes of motor neuron degeneration have been suggested for ALS, none has yet been proven responsible. Results of recent research have implicated toxic 44

molecular fragments known as free radicals. Some evidence suggests that a cascade of events leads to excess free radical production inside motor neurons, leading to their death. Why free radicals should be produced in excess amounts is unclear, as is whether this excess is the cause or the effect of other degenerative processes. Additional agents within this toxic cascade may include excessive levels of a neurotransmitter known as glutamate, which may over-stimulate motor neurons, thereby increasing free-radical production, and a faulty detoxification enzyme known as SOD-1, for superoxide dismutase type 1. The actual pathway of destruction is not known, however, nor is the trigger for the rapid degeneration that marks ALS. Further research may show that other pathways are involved, perhaps ones even more important than this one. Autoimmune factors or premature aging may play some role, as could viral agents or environmental toxins. Two major forms of ALS are known: familial and sporadic. Familial ALS accounts for about 10% of all ALS cases. As the name suggests, familial ALS is believed to be caused by the inheritance of one or more faulty genes. About 15% of families with this type of ALS have mutations in the gene for SOD-1. SOD-1 gene defects are dominant, meaning only one gene copy is needed to develop the disease. Therefore, a parent with the faulty gene has a 50% chance of passing the gene along to a child. Sporadic ALS has no known cause. While many environmental toxins have been suggested as causes, to date no research has confirmed any of the candidates investigated, including aluminum and mercury and lead from dental fillings. As research progresses, it is likely that many cases of sporadic ALS will be shown to have a genetic basis as well. A third type, called Western Pacific ALS, occurs in Guam and other Pacific islands. This form combines symptoms of both ALS and Parkinson’s disease. Symptoms The earliest sign of ALS is most often weakness in the arms or legs, usually more pronounced on one side than the other at first. Loss of function is usually more rapid in the legs among people with familial ALS and in the arms among those with sporadic ALS. Leg weakness may first become apparent by an increased frequency of stumbling on uneven pavement, or an unexplained difficulty climbing stairs. Arm weakness may lead to difficulty grasping and holding a cup, for instance, or loss of dexterity in the fingers. Less often, the earliest sign of ALS is weakness in the bulbar muscles, those muscles in the mouth and throat that control chewing, swallowing, and speaking. A person with bulbar weakness may become hoarse or tired after speaking at length, or speech may become slurred.

GALE ENCYCLOPEDIA OF NEUROLOGICAL DISORDERS

Normal nerve fiber

Amyotrophic lateral sclerosis

NORMAL SPINAL NEURON

DISEASED SPINAL NEURON

Affected nerve fiber

Normal skeletal muscle

Wasted skeletal muscle

Amyotrophic lateral sclerosis (ALS) is caused by the degeneration and death of motor neurons in the spinal cord and brain. These neurons convey electrical messages from the brain to the muscles to stimulate movement in the arms, legs, trunk, neck, and head. As motor neurons degenerate, the muscles are weakened and cannot move as effectively, leading to muscle wasting. (Illustration by Electronic Illustrators Group.)

In addition to weakness, the other cardinal signs of ALS are muscle wasting and persistent twitching (fasciculation). These are usually seen after weakness becomes obvious. Fasciculation is quite common in people without the disease, and is virtually never the first sign of ALS. While initial weakness may be limited to one region, ALS almost always progresses rapidly to involve virtually all the voluntary muscle groups in the body. Later symptoms include loss of the ability to walk, to use the arms and hands, to speak clearly or at all, to swallow, and to hold the head up. Weakness of the respiratory muscles makes breathing and coughing difficult, and poor swallowing control increases the likelihood of inhaling food or saliva (aspiration). Aspiration increases the likelihood of lung infection, which is often the cause of death. With a ventilator and scrupulous bronchial hygiene, a person with ALS

may live much longer than the average, although weakness and wasting will continue to erode any remaining functional abilities. Most people with ALS continue to retain function of the extraocular muscles that move their eyes, allowing some communication to take place with simple blinks or through use of a computer-assisted device.

Diagnosis The diagnosis of ALS begins with a complete medical history and physical exam, plus a neurological examination to determine the distribution and extent of weakness. An electrical test of muscle function, called an electromyogram, or EMG, is an important part of the diagnostic process. Various other tests, including blood and urine tests, x rays, and CT scans, may be done to rule out other possible causes of the symptoms, such as tumors of

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Amyotrophic lateral sclerosis

the skull base or high cervical spinal cord, thyroid disease, spinal arthritis, lead poisoning, or severe vitamin deficiency. ALS is rarely misdiagnosed following a careful review of all these factors.

Treatment There is no cure for ALS, and no treatment that can significantly alter its course. There are many things which can be done, however, to help maintain quality of life and to retain functional ability even in the face of progressive weakness. As of early 1998, only one drug had been approved for treatment of ALS. Riluzole (Rilutek) appears to provide on average a three-month increase in life expectancy when taken regularly early in the disease, and shows a significant slowing of the loss of muscle strength. Riluzole acts by decreasing glutamate release from nerve terminals. Experimental trials of nerve growth factor have not demonstrated any benefit. No other drug or vitamin currently available has been shown to have any effect on the course of ALS. A physical therapist works with an affected person and family to implement exercise and stretching programs to maintain strength and range of motion, and to promote general health. Swimming may be a good choice for people with ALS, as it provides a low-impact workout to most muscle groups. One result of chronic inactivity is contracture, or muscle shortening. Contractures limit a person’s range of motion, and are often painful. Regular stretching can prevent contracture. Several drugs are available to reduce cramping, a common complaint in ALS. An occupational therapist can help design solutions to movement and coordination problems, and provide advice on adaptive devices and home modifications. Speech and swallowing difficulties can be minimized or delayed through training provided by a speech-language pathologist. This specialist can also provide advice on communication aids, including computer-assisted devices and simpler word boards. Nutritional advice can be provided by a nutritionist. A person with ALS often needs softer foods to prevent jaw exhaustion or choking. Later in the disease, nutrition may be provided by a gastrostomy tube inserted into the stomach. Mechanical ventilation may be used when breathing becomes too difficult. Modern mechanical ventilators are small and portable, allowing a person with ALS to maintain the maximum level of function and mobility. Ventilation may be administered through a mouth or nose piece, or through a tracheostomy tube. This tube is inserted through a small hole made in the windpipe. In addition to 46

providing direct access to the airway, the tube also decreases the risk aspiration. While many people with rapidly progressing ALS choose not to use ventilators for lengthy periods, they are increasingly being used to prolong life for a short time. The progressive nature of ALS means that most persons will eventually require full-time nursing care. This care is often provided by a spouse or other family member. While the skills involved are not difficult to learn, the physical and emotional burden of care can be overwhelming. Caregivers need to recognize and provide for their own needs as well as those of people with ALS, to prevent depression, burnout, and bitterness. Throughout the disease, a support group can provide important psychological aid to affected persons and their caregivers as they come to terms with the losses ALS inflicts. Support groups are sponsored by both the ALS Society and the Muscular Dystrophy Association.

Alternative treatment Given the grave prognosis and absence of traditional medical treatments, it is not surprising that a large number of alternative treatments have been tried for ALS. Two studies published in 1988 suggested that amino-acid therapies may provide some improvement for some people with ALS. While individual reports claim benefits for megavitamin therapy, herbal medicine, and removal of dental fillings, for instance, no evidence suggests that these offer any more than a brief psychological boost, often followed by a more severe letdown when it becomes apparent the disease has continued unabated. However, once the causes of ALS are better understood, alternative therapies may be more intensively studied. For example, if damage by free radicals turns out to be the root of most of the symptoms, antioxidant vitamins and supplements may be used more routinely to slow the progression of ALS. Or, if environmental toxins are implicated, alternative therapies with the goal of detoxifying the body may be of some use.

Prognosis ALS usually progresses rapidly, and leads to death from respiratory infection within three to five years in most cases. The slowest disease progression is seen in those who are young and have their first symptoms in the limbs. About 10% of people with ALS live longer than eight years.

Prevention There is no known way to prevent ALS or to alter its course.

GALE ENCYCLOPEDIA OF NEUROLOGICAL DISORDERS

BOOKS

Adams, Raymond D., Maurice Victor, and Allan H. Ropper. Adams’ & Victor’s Principles of Neurology, 6th ed. New York: McGraw Hill, 1997. Brown, Robert H. “The motor neuron diseases.” In Harrison’s Principles of Internal Medicine, 14th ed., edited by Anthony S. Fauci, et al., pp. 2368-2372. New York: McGraw-Hill, 1998. Feldman, Eva L. “Motor neuron diseases.” In Cecil Textbook of Medicine, 21st ed., edited by Lee Goldman and J. Claude Bennett, pp. 2089-2092. Philadelphia: W. B. Saunders, 2000. Kimura, Jun, and Ryuji Kaji. Physiology of ALS and Related Diseases. Amsterdam: Elsevier Science, 1997. Mitsumoto, Hiroshi, David A. Chad, Erik Pioro, and Sid Gilman. Amyotrophic Lateral Sclerosis. New York: Oxford University Press, 1997.

Muscular Dystrophy Association. 3300 East Sunrise Drive, Tucson, AZ 85718-3208. (520) 529-2000 or (800) 5721717; Fax: (520) 529-5300. . WEBSITES

ALS Society of Canada. . ALS Survival Guide. . American Academy of Family Physicians. . National Organization for Rare Diseases. . National Institute of Neurological Disorders and Stroke. . National Library of Medicine. . World Federation of Neurology. .

PERIODICALS

Ansevin, C. F. “Treatment of ALS with pleconaril.” Neurology 56, no. 5 (2001): 691-692. Eisen, A., and M. Weber. “The motor cortex and amyotrophic lateral sclerosis.” Muscle and Nerve 24, no. 4 (2001): 564-573. Gelanis, D. F. “Respiratory Failure or Impairment in Amyotrophic Lateral Sclerosis.” Current treatment options in neurology 3, no. 2 (2001): 133-138. Ludolph, A. C. “Treatment of amyotrophic lateral sclerosis— what is the next step?” Journal of Neurology 246, Suppl 6 (2000): 13-18. Pasetti, C., and G. Zanini. “The physician-patient relationship in amyotrophic lateral sclerosis.” Neurological Science 21, no. 5 (2000): 318-323. Robberecht, W. “Genetics of amyotrophic lateral sclerosis.” Journal of Neurology 246, Suppl 6 (2000): 2-6. Robbins, R. A., Z. Simmons, B. A. Bremer, S. M. Walsh, and S. Fischer. “Quality of life in ALS is maintained as physical function declines.” Neurology 56, no. 4 (2001): 442-444. ORGANIZATIONS

ALS Association of America. 27001 Agoura Road, Suite 150, Calabasas Hills, CA 91301-5104. (800) 782-4747 (Information and Referral Service) or (818) 880-9007; Fax: (818) 880-9006. American Academy of Family Physicians. 11400 Tomahawk Creek Parkway, Leawood, KS 66211-2672. (913) 9066000. [email protected]. . American Academy of Neurology. 1080 Montreal Avenue, St. Paul, Minnesota 55116. (651) 695-1940; Fax: (651) 6952791. [email protected]. . American Medical Association, 515 N. State Street, Chicago, IL 60610. (312) 464-5000. . Centers for Disease Control and Prevention. 1600 Clifton Road, Atlanta, GA 30333. (404) 639-3534 or (800) 3113435. , .

L. Fleming Fallon, Jr., MD, DrPH

❙ Anatomical nomenclature

Over the centuries, anatomists developed a standard nomenclature, or method of naming anatomical structures. Terms such as “up” or “down” obviously have no meaning unless the orientation of the body is clear. When a body is lying on its back, the thorax and abdomen are at the same level. The upright sense of up and down is lost. Further, because anatomical studies and particularly embryological studies were often carried out in animals, the development of the nomenclature relative to comparative anatomy had an enormous impact on the development of human anatomical nomenclature. There were obvious difficulties in relating terms from quadrupeds (animals that walk on four legs) who have abdominal and thoracic regions at the same level as opposed to human bipeds in whom an upward and downward orientation might seem more obvious. In order to standardize nomenclature, anatomical terms relate to the standard anatomical position. When the human body is in the standard anatomical position it is upright, erect on two legs, facing frontward, with the arms at the sides each rotated so that the palms of the hands turn forward. In the standard anatomical position, superior means toward the head or the cranial end of the body. The term inferior means toward the feet or the caudal end of the body.

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Anatomical nomenclature

Resources

Anatomical nomenclature

The frontal surface of the body is the anterior or ventral surface of the body. Accordingly, the terms “anteriorly” and “ventrally” specify a position closer to—or toward—the frontal surface of the body. The back surface of the body is the posterior or dorsal surface and the terms “posteriorly” and “dorsally” specify a position closer to— or toward—the posterior surface of the body. The terms superficial and deep relate to the distance from the exterior surface of the body. Cavities such as the thoracic cavity have internal and external regions that correspond to deep and superficial relationships in the midsagittal plane. The bones of the skull are fused by sutures that form important anatomical landmarks. Sutures are joints that run jaggedly along the interface between the bones. At birth, the sutures are soft, broad, and cartilaginous. The sutures eventually fuse and become rigid and ossified near the end of puberty or early in adulthood. The sagittal suture unties the parietal bones of the skull along the midline of the body. The suture is used as an anatomical landmark in anatomical nomenclature to establish what are termed sagittal planes of the body. The primary sagittal plane is the sagittal plane that runs through the length of the sagittal suture. Planes that are parallel to the sagittal plane, but that are offset from the midsagittal plane are termed parasagittal planes. Sagittal planes run anteriorly and posteriorly, are always at right angles to the coronal planes. The medial plane or midsagittal plane divides the body vertically into superficially symmetrical right and left halves. The medial plane also establishes a centerline axis for the body. The terms medial and lateral relate positions relative to the medial axis. If a structure is medial to another structure, the medial structure is closer to the medial or center axis. If a structure is lateral to another structure, the lateral structure is farther way from the medial axis. For example, the lungs are lateral to the heart. The coronal suture unites the frontal bone with the parietal bones. In anatomical nomenclature, the primary coronal plane designates the plane that runs through the length of the coronal suture. The primary coronal plane is also termed the frontal plane because it divides the body into frontal and back halves. Planes that divide the body into superior and inferior portions, and that are at right angles to both the sagittal and coronal planes are termed transverse planes. Anatomical planes that are not parallel to sagittal, coronal, or transverse planes are termed oblique planes. The body is also divided into several regional areas. The most superior area is the cephalic region that includes the head. The thoracic region is commonly known as the chest region. Although the celiac region more specifically

48

refers to the center of the abdominal region, celiac is sometimes used to designate a wider area of abdominal structures. At the inferior end of the abdominal region lies the pelvic region or pelvis. The posterior or dorsal side of the body has its own special regions, named for the underlying vertebrae. From superior to inferior along the midline of the dorsal surface lie the cervical, thoracic, lumbar, and sacral regions. The buttocks are the most prominent feature of the gluteal region. The term upper limbs or upper extremities refers to the arms. The term lower limbs or lower extremities refers to the legs. The proximal end of an extremity is at the junction of the extremity (i.e., arm or leg) with the trunk of the body. The distal end of an extremity is the point on the extremity farthest away from the trunk (e.g., fingers and toes). Accordingly, if a structure is proximate to another structure it is closer to the trunk (e.g., the elbow is proximate to the wrist). If a structure is distal to another, it is farther from the trunk (e.g., the fingers are distal to the wrist). Structures may also be described as being medial or lateral to the midline axis of each extremity. Within the upper limbs, the terms radial and ulnar may be used synonymous with lateral and medial. In the lower extremities, the terms fibular and tibial may be used as synonyms for lateral and medial. Rotations of the extremities may de described as medial rotations (toward the midline) or lateral rotations (away from the midline). Many structural relationships are described by combined anatomical terms (e.g., the eyes are anterio-medial to the ears). There are also terms of movement that are standardized by anatomical nomenclature. Starting from the anatomical position, abduction indicates the movement of an arm or leg away from the midline or midsagittal plane. Adduction indicates movement of an extremity toward the midline. The opening of the hands into the anatomical position is supination of the hands. Rotation so the dorsal side of the hands face forward is termed pronation. The term flexion means movement toward the flexor or anterior surface. In contrast, extension may be generally regarded as movement toward the extensor or posterior surface. Flexion occurs when the arm brings the hand from the anatomical position toward the shoulder (a curl) or when the arm is raised over the head from the anatomical position. Extension returns the upper arm and or lower to the anatomical position. Because of the embryological rotation of the lower limbs that rotates the primitive dorsal

GALE ENCYCLOPEDIA OF NEUROLOGICAL DISORDERS

The term palmar surface (palm side) is applied to the flexion side of the hand. The term plantar surface is applied to the bottom sole of the foot. From the anatomical position, extension occurs when the toes are curled back and the foot arches upward and flexion occurs as the foot is returned to anatomical position. Rolling motions of the foot are described as inversion (rolling with the big toe initially lifting upward) and eversion (rolling with the big toe initially moving downward). K. Lee Lerner

❙ Anencephaly

Key Terms Alpha-fetoprotein (AFP) A chemical substance produced by the fetus and found in the fetal circulation.

Causes and symptoms As an isolated defect, anencephaly appears to be caused by a combination of genetic factors and environmental influences that predispose to faulty formation of the nervous system. The specific genes and environmental insults that contribute to this multifactorial causation are not completely understood. It is known that nutritional insufficiency, specifically folic acid insufficiency, is one predisposing environmental factor, and that mutations of genes involved in folic acid metabolism are genetic risk factors. The recurrence risk after the birth of an infant with anencephaly is 3–5%. The recurrence may be anencephaly or another neural tube defect such as spina bifida. Anencephaly is readily apparent at birth because of exposure of all or part of the brain. Not only is the brain malformed, but it is also damaged because of the absence of the overlying protective encasement.

Definition

Anencephaly is a lethal birth defect characterized by the absence of all or part of the skull and scalp and malformation of the brain.

Description Anencephaly is one of a group of malformations of the central nervous system collectively called neural tube defects. Anencephaly is readily apparent at birth because of the absence of the skull and scalp and exposure of the underlying brain. The condition is also called acrania (absence of the skull) and acephaly (absence of the head). In its most severe form, the entire skull and scalp are missing. In some cases, termed “meroacrania” or “meroanencephaly,” a portion of the skull may be present. In most instances, anencephaly occurs as an isolated birth defect with the other organs and tissues of the body forming correctly. In approximately 10% of cases, other malformations coexist with anencephaly.

Demographics Anencephaly occurs in all races and ethnic groups. The prevalence rates range from less than one in 10,000 births (European countries) to more than 10 per 10,000 births (Mexico, China).

Diagnosis Anencephaly is diagnosed by observation. Prenatal diagnosis may be made by ultrasound examination after 12–14 weeks’ gestation. Prenatal diagnosis of anencephaly can also be detected through maternal serum alpha-fetoprotein screening. The level of alpha-fetoprotein in the maternal blood is elevated because of the leakage of this fetal protein into the amniotic fluid. There are no treatments for anencephaly. A pregnant woman or couple expecting an anencephalic baby will need a sensitive and supportive health care team, and perhaps some additional psychological support as they face the inevitable death of their infant, usually before or shortly after birth.

Treatment and management No treatment is indicated for anencephaly. Affected infants are stillborn or die within the first few days of life. The risk for occurrence or recurrence of anencephaly may be reduced by half or more by the intake of folic acid during the months immediately before and after conception. Natural folic acid, a B vitamin, may be found in many foods (green leafy vegetables, legumes, orange juice, liver). Synthetic folic acid may be obtained in vitamin preparations and in certain fortified breakfast cereals. In

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Anencephaly

side to the adult form ventral side, flexion occurs as the thigh is raised anteriorly and superiorly toward the anterior portion of the pelvis. Extension occurs when the thigh is returned to anatomical position. Specifically, due to the embryological rotation, flexion of the lower leg occurs as the foot is raised toward the back of the thigh and extension of the lower leg occurs with the kicking motion that returns the lower leg to anatomical position.

Anencephaly

Diagram of Anencephaly NORMAL INFANT

ANENCEPHALIC INFANT

Brain

Brain Stem

Brain Stem

Infants born with anencephaly have either a severely underdeveloped brain or total brain absence. A portion of the brainstem usually protrudes through the skull, which also fails to develop properly. (Gale Group.)

the United States, all enriched cereal grain flours have been fortified with folic acid.

National Birth Defects Prevention Network. Atlanta, GA. (770) 488-3550. .

Roger E. Stevenson, MD Rosalyn Carson-DeWitt, MD

Clinical Trials Research is primarily directed at understanding the underlying factors that affect early neurological development in the fetus.

❙ Aneurysms

Prognosis Anencephaly is uniformly fatal at birth or soon thereafter. Resources PERIODICALS

Czeizel, A. E., and I. Dudas. “Prevention of the First Occurrence of Neural Tube Defects by Preconceptional Vitamin Supplementation.” New England Journal of Medicine 327 (1992): 1832–1835. Medical Research Council Vitamin Study Research Group. “Prevention of Neural Tube Defects: Results of the Medical Research Council Vitamin Study.” Lancet 338 (1991): 131–137. Sells, C. J., and J. G. Hall. “Neural Tube Defects.” Mental Retardation and Developmental Disabilities Research Reviews 4, no. 4, 1998.

Cerebral aneurysm is the enlargement, distention, dilation, bulging, or ballooning of the wall of a cerebral artery or vein. Aneurysms affect arteries throughout the body, including blood vessels in the brain (intracerebral aneurysm). Ruptures of intracerebral aneurysm result in stroke (loss of blood supply to tissue) and bleeding into the subarachnoid space). The most common aneurysm is an abdominal aneurysm.

Description

ORGANIZATIONS

March of Dimes Birth Defects Foundation. 1275 Mamaroneck Ave., White Plains, NY 10605. (888) 663-4637. [email protected]. .

50

Definition

Dilations, or ballooning, of blood vessels to form an aneurysm are particularly dangerous because they increase the chance of arterial rupture and subsequent bleeding into brain tissues (a hemorrhagic stroke). Rupture of an aneurysm can lead to the leakage of blood into the tissues and spaces surrounding the brain. This leaked blood then clots to form an intracranial hematoma. Aneurysms that rupture can result in severe disability or death.

GALE ENCYCLOPEDIA OF NEUROLOGICAL DISORDERS

Aneurysms

Key Terms Aneurysm A bulging, weakened area in a blood vessel.

Common complications of cerebral aneurysms that leak include hydrocephalus (the excessive accumulation of cerebrospinal fluid) and persistent spasms of blood vessels that adversely affect the maintenance of arterial blood pressure. Once they rupture or bleed, aneurysms have a tendency toward recurrent bleeding episodes. This tendency to rebleed is particularly high in the first few days following the initial bleed. Intracerebral bleeds are often accompanied by increases in cerebrospinal fluid and an increased intracranial pressure (hydrocephalus). Once they occur, aneurysms are dynamic and can increase in size over time. The increase in size is not always linear and can advance sporadically until they expand to a critical size. As they grow, aneurysms begin to put pressure on surrounding tissues. In addition, as they grow, aneurysms usually result in progressively more difficult problems. The larger the size of an aneurysm, regardless of location, the greater the chance it will ultimately bleed. Cerebral aneurysm ruptures usually lead to subarachnoid hemorrhage (SAH).

Demographics Although more common in adults than children, cerebral aneurysms occur in all age groups. Cerebral aneurysms are more common—and the risk of aneurysm generally increases—with age. Aneurysm sufferers are rarely young; the incidence of aneurysm is low in those under 20 years of age. In contrast, aneurysms are relatively common in people over 65 years of age. Risk indicators for some groups such as Caucasian males begin to increase at age 55. Some studies indicate that up to 5% of the population over 65 suffer some form of aneurysm. Incidence of specific aneurysms varies, but in general within the United States they are occur less frequently in Caucasian women, and are relatively uncommon in African Americans. Of those affected with an aneurysm anywhere in the body, the National Institute of Health (NIH) estimates that approximately 30,000 people in the United States will suffer an aneurysm rupture.

Arteriograph of the head from behind, showing an aneurysm, the balloon-like smooth swelling just below and to the right of center. (CNRI/National Audubon Society Collection/Photo Researchers, Inc. Reproduced by permission.)

Cigarette smoking and excess alcohol use substantially increase the risk of aneurysm rupture.

Causes and symptoms An aneurysm may be a congenital defect in the structure of the muscular wall of affected blood vessels (e.g., the intima of an artery), or arise secondary to trauma, atherosclerosis, or high blood pressure. The defect results in an abnormal thinning of the arterial or venous wall that makes the wall subsequently susceptible to aneurysm. Research data appears to show that some individuals have a basic genetic susceptibility or predisposition to aneurysms. The genetic inheritance patterns resemble characteristics linked to an autosomal dominant gene. Within some families, rates of aneurysms can run as high as five to 10 times those found in the general population. Direct causes of intracerebral aneurysms include infection, trauma, or neoplastic disease. If infection is the cause, the infection may be from a remote site. For example, an aneurysm in the brain may result from the loosed embolus such as plaque, fatty deposit, clot, or clump of cells, originating at an infection in another part of the body. The embolus is transported to the site of the future cerebral aneurysm by the bloodstream and cerebral circulation. An aneurysm formed in this manner is termed a mycotic aneurysm.

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Aneurysms

Prior to rupture, the symptoms associated with an aneurysm depend upon its location, size, and rate of expansion. A static aneurysm that does not leak (bleed) or adversely affect cerebral circulation or neighboring tissue may be asymptomatic (without symptoms). In contrast, larger aneurysms or aneurysms with a rapid growth rate may produce pronounced symptoms such as swelling, loss of sensation, blurred vision, etc. Just prior to an aneurysm rupture, patients typically experience some symptoms commonly associated with stroke. Depending on the size and location of the aneurysm about to rupture, a patient may suffer a severe headache, deterioration or disturbances of hearing, and disturbances of vision such as double vision, severe nausea and vomiting, and syncopal episodes (periodic fainting or loss of consciousness). A severe headache that is unresponsive to standard analgesics is the most common sign of a leaking or bleeding aneurysm. Many patients experience a series of sentinel (warning) headaches if the aneurysm begins to leak prior to rupture. A fully ruptured aneurysm presents with a severe headache that is frequently accompanied by fainting or temporary (transient) loss of consciousness, often with severe nausea, vomiting, and rapidly developing stiff neck (nuchal rigidity). Aneurysms normally rupture while the patient is active and awake.

Diagnosis The severe headache that accompanies a cerebral aneurysm is often the principle complaint upon which the diagnosis of aneurysm begins to build. Angiography provides the most definitive diagnosis of an intracerebral aneurysm by determining the specific site of the aneurysm. A computed tomography (CT) scan can also diagnose a bleeding cerebral aneurysm. Arteriography is an x ray of the carotid artery taken when a special dye is injected into the artery. The presence of blood in the cerebrospinal fluid withdrawn during a lumbar puncture is also diagnostic evidence for blood leaking into the subarachnoid space. Magnetic resonance imaging (MRI) studies can also be useful in accessing the extent of damage to surrounding tissues and are often used to study aneurysms prior to leakage or rupture. MRI uses magnetic fields to detect subtle changes in brain tissue content. The benefit of MRI over CT imaging is that MRI is better able to localize the exact anatomical position of an aneurysm. Other types of MRI scans are magnetic resonance angiography (MRA) and functional magnetic resonance imaging (fMRI). Neurosurgeons use MRA to detect stenosis (blockage) of the brain arteries inside the skull by mapping 52

flowing blood. Functional MRI uses a magnet to pick up signals from oxygenated blood and can show brain activity through increases in local blood flow. Duplex Doppler ultrasound and arteriography are two additional diagnostic imaging techniques used to decide if an individual would benefit from a surgical procedure called carotid endarterectomy. This surgery is used to remove fatty deposits from the carotid arteries and can help prevent stroke. Doppler ultrasound is a painless, noninvasive test in which sound waves bounce off the moving blood and the tissue in the artery and can be formed into an image.

Treatment team Management and treatment of aneurysms require a multi-disciplinary team. Physicians are responsible for caring for general health and providing guidance aimed at preventing a stroke. Neurologists and neurosurgeons usually lead acute-care teams and direct patient care during hospitalization and recovery from surgery. Neuroradiologists help pinpoint the location and extent of aneurysms.

Treatment Treatment for ruptures of cerebral aneurysms includes measures to stabilize the emergency by assuring cardiopulmonary functions (adequate heart rate and respiration) while simultaneously moving to decrease intracranial pressure and surgically clip (repair and seal) the ruptured cerebral aneurysm. Surgery is often performed as soon as the patient is stabilized; ideally within 72 hours of the onset of rupture. The goal of surgery is to prevent rebleeding. Surgery is performed to expose the aneurysm and allow the placement of a clip across a strong portion of the vessel to obstruct the flow of blood through the weakened aneurysm. Repeat surgical procedures to seal an aneurysm are not uncommon. Treatment of unruptured aneurysms is certainly less dramatic, but presents a more deliberate and complex path. Microcoil thrombosis or balloon embolization (the insertion via the arterial catheter of a balloon or other obstruction that blocks blood flow through the region of aneurysm) are alternatives to full surgical intervention. Other nonsurgical interventions include rest, medications, and hypertensive-hypervolemic therapy to drive blood around obstructed vessels. Treatment decisions are made between the treatment team and family members with regard to the best course of treatment and the probable outcomes for patients suffering a severe aneurysm rupture with extensive damage to surrounding brain tissue. Asymptomatic aneurysms allow the treatment team to more fully evaluate surgical and nonsurgical options.

GALE ENCYCLOPEDIA OF NEUROLOGICAL DISORDERS

The recovery and rehabilitation of patients suffering a cerebral aneurysm depend on the location and size of the aneurysm. The course of recovery and rehabilitation is also heavily influenced by whether the aneurysm ruptures. Key to recovery is the prevention of aneurysm rebleeding, the management of swelling in the ventricular system (hydrocephalus), seizures, cardiac arrhythmias, and vasospasm. The onset of vasospasm within the first two weeks of the initial bleeding incident is the major cause of death in those who survive the initial rupture of the aneurysm. Ventricular drains are used to control the buildup of cerebrospinal fluid in the ventricular system.

Clinical trials As of May 2004, current studies sponsored by the National Institute of Neurological Disorders and Stroke (NINDS) include a study on the effect of the drug ProliNO on brain artery spasms after aneurysm rupture and a study of the role of genetics on the development of intracranial aneurysms (Familial Intracranial Aneurysm Study). Further information is available at .

Prognosis The overall prognosis for a patient with a cerebral aneurysm depends on several factors including the size, location, and stability of the aneurysm. Facets of the patient’s general health, neurological health, age, and familial history must also be evaluated in forming a prognosis. Although each patient is different, and each aneurysm must be individually evaluated, in general, the prognosis for patients who have suffered a bleed is guarded at best, with mortality rates up 60% within a year of the initial bleeding incident. Approximately half of the survivors suffer some long-lasting disability. Patients with cerebral aneurysm can, however, fully recover with no long-lasting disorder. Data regarding the prognosis for unruptured aneurysms is more tentative and not specific for cerebral aneurysms. Some long-term studies give evidence that only 10% of patients might suffer leakage or bleeding from their aneurysm over a period of 10 years and only about a quarter of patients would experience bleeding from the aneurysm over a period of 25 years.

Special concerns Intracerebral aneurysms are sometimes associated with other diseases such as fibromuscular hyperplasia or other disorders such as high blood pressure (although

aneurysms also occur in persons with normal blood pressure. Other physiological stresses such as pregnancy have not been demonstrated to have a correlation to the rupture of cerebral aneurysm. Resources BOOKS

Bear, M., et al. Neuroscience: Exploring the Brain. Baltimore: Williams & Wilkins, 1996. Goetz, C. G., et al. Textbook of Clinical Neurology. Philadelphia: W.B. Saunders Co., 1999. Goldman, Cecil. Textbook of Medicine, 21st ed. New York: W.B. Saunders Co., 2000. Guyton & Hall. Textbook of Medical Physiology, 10th ed. New York: W.B.Saunders Co., 2000. Wiebers, David. Stroke-Free for Life: The Complete Guide to Stroke Prevention and Treatment. New York: Harper, 2002. OTHER

“Stroke Risk Factors.” American Stroke Association. April 20, 2004 (May 22, 2004). . ORGANIZATIONS

American Stroke Association: A Division of American Heart Association. 7272 Greenville Avenue, Dallas, TX 75231-4596. (214) 706-5231 or (888) 4STROKE (478-7653). [email protected]. . Brain Aneurysm Foundation. 12 Clarendon Street, Boston, MA 02116. (617) 723-3870; Fax: (617) 723-8672. [email protected]. . National Stroke Association. 9707 East Easter Lane, Englewood, CO 80112-3747. (303) 649-9299 or (800) STROKES (787-6537); Fax: (303) 649-1328. [email protected]. .

Paul Arthur

❙ Angelman syndrome Definition

Angelman syndrome (AS) is a genetic condition that causes severe mental retardation, severe speech impairment, and a characteristic happy and excitable demeanor.

Description Individuals with AS show evidence of delayed development by 6–12 months of age. Eventually, this delay is recognized as severe mental retardation. Unlike some genetic conditions causing severe mental retardation, AS is

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Angelman syndrome

Recovery and rehabilitation

Angelman syndrome

Angelman Syndrome 1. Etiology: Deletion, Uniparental Disomy, or Unknown

88y

d.71y

61y

36y

d.83y Colon cancer

54y

23y

49y

18y

2. Etiology: UBE3A mutation, Imprinting mutation, or Unknown

78y

46y

d.71y d.88y Liver cirrhosis

63y

39y

60y

d.62y Stroke

48y

25y 21y 17y 14y

12y

75y

39y

12y d.2mos Congenital heart defect

2 2y

See Symbol Guide for Pedigree Charts. (Gale Group.)

not associated with developmental regression (loss of previously attained developmental milestones). Severe speech impairment is a striking feature of AS. Speech is almost always limited to a few words. However, receptive language skills (listening to and understanding the speech of others) and non-verbal communication are not as severely affected. Individuals with AS have a balance disorder, causing unstable and jerky movements. This typically includes gait ataxia (a slow, unbalanced way of walking) and tremulous movements of the limbs. AS is also associated with a unique “happy” behavior, which may be the best-known feature of the condition. This may include frequent laughter or smiling, often with no apparent stimulus. Children with AS often appear happy, excited, and active. They may also sometimes flap their hands repeatedly. Generally, they have a short attention span. These characteristic behaviors led to the original name of this condition, the “Happy Puppet” syndrome. However, this name is no longer used as it is considered insensitive to AS individuals and their families.

Demographics AS has been reported in individuals of diverse ethnic backgrounds. The incidence of the condition is estimated at 1/10,000 to 1/30,000. 54

Causes and symptoms Most cases of AS have been traced to specific genetic defects on chromosomes received from the mother. In about 8% of individuals with AS, no genetic cause can be identified. This may reflect misdiagnosis, or the presence of additional, unrecognized mechanisms leading to AS. The first abnormalities noted in an infant with AS are often delays in motor milestones (those related to physical skills, such as sitting up or walking), muscular hypotonia (poor muscle tone), and speech impairment. Some infants seem unaccountably happy and may exhibit fits of laughter. By age 12 months, 50% of infants with AS have microcephaly (a small head size). Tremulous movements are often noted during the first year of life. Seizures occur in 80% of children with AS, usually by three years of age. No major brain lesions are typically seen on cranial imaging studies. The achievement of walking is delayed, usually occurring between two-and-a-half and six years of age. The child with AS typically exhibits a jerky, stiff gait, often with uplifted and bent arms. About 10% of individuals with AS do not walk. Additionally, children may have drooling, protrusion of the tongue, hyperactivity, and a short attention span. Many children have a decreased need for sleep and abnormal sleep/wake cycles. This problem may emerge in

GALE ENCYCLOPEDIA OF NEUROLOGICAL DISORDERS

Diagnosis The clinical diagnosis of AS is made on the basis of physical examination and medical and developmental history. Confirmation requires specialized laboratory testing. There is no single laboratory test that can identify all cases of AS. Several different tests may be performed to look for the various genetic causes of AS. When positive, these tests are considered diagnostic for AS. These include DNA methylation studies, UBE3A mutation analysis, and fluorescent in situ hybridization (FISH).

Individuals with AS may be more likely to develop particular medical problems which are treated accordingly. Newborn babies may have difficulty feeding and special bottle nipples or other interventions may be necessary. Gastroesophageal reflux (heartburn) may lead to vomiting or poor weight gain and may be treated with drugs or surgery. Constipation is a frequent problem and is treated with laxative medications. Many individuals with AS have strabismus (crossed eyes), which may require surgical correction. Orthopedic problems, such as tightening of tendons or scoliosis, are common. These problems may be treated with physical therapy, bracing, or surgery.

Prognosis Individuals with AS have significant mental retardation and speech impairment that are considered to occur in all cases. However, they do have capacity to learn and should receive appropriate educational training. Young people with AS typically have good physical health aside from seizures. Although life span data are not available, the life span of people with AS is expected to be normal.

Special concerns Educational concerns

Treatment team Children with Angelman syndrome will need help from a variety of professionals, including a general pediatrician and pediatric neurologist. A child psychiatrist and/or psychologist may be helpful as well, particularly to help design and implement various behavioral plans. Physical, occupational, and speech and language therapists may help support specific deficits. A learning specialist may be consulted for help with an individualized educational plan.

Treatment There is no specific treatment for AS. A variety of symptomatic management strategies may be offered for hyperactivity, seizures, mental retardation, speech impairment, and other medical problems. The typical hyperactivity in AS may not respond to traditional behavior modification strategies. Children with AS may have a decreased need for sleep and a tendency to awaken during the night. Drug therapy may be prescribed to counteract hyperactivity or aid sleep. Most families make special accommodations for their child by providing a safe yet confining environment. Seizures in AS are usually controllable with one or more anti-seizure medications. In some individuals with severe seizures, dietary manipulations may be tried in combination with medication.

Children with AS appear to benefit from targeted educational training. Physical and occupational therapy may improve the disordered, unbalanced movements typical of AS. Children with a severe balance disorder may require special supportive chairs. Speech therapy is often directed towards the development of nonverbal communication strategies, such as picture cards, communication boards, or basic signing gestures. Legal issues The most pressing long-term concern for patients with AS is working out a life plan for ongoing care, since many are likely to outlive their parents. The parents of a child diagnosed with AS should consult an estate planner, an attorney, and a certified public accountant (CPA) in order to draft a life plan and letter of intent. A letter of intent is not a legally binding document, but it gives the patient’s siblings and other relatives or caregivers necessary information on providing for her in the future. The attorney can help the parents decide about such matters as guardianship as well as guide them through the legal process of appointing a guardian, which varies from state to state. Resources PERIODICALS

“Angelman syndrome.” The Exceptional Parent 30, no. 3 (March 2000): S2.

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infancy and persist throughout childhood. Upon awakening at night, children may become very active and destructive to bedroom surroundings. The language impairment associated with AS is severe. Most children with AS fail to learn appropriate and consistent use of more than a few words. Receptive language skills are less severely affected. Older children and adults are able to communicate by using gestures or communication boards (special devices bearing visual symbols corresponding to commonly used expressions or words). Some individuals with AS may have a lighter skin complexion than would be expected given their family background.

Angiography

Lombroso, Paul J. “Genetics of Childhood Disorders: XVI. Angelman Syndrome: A Failure to Process.” Journal of the American Academy of Child and Adolescent Psychiatry 39, no. 7 (July 2000): 931. ORGANIZATION

Angelman Syndrome Foundation, Inc. 414 Plaza Drive, Suite 209, Westmont, IL 60559. (800) IF-ANGEL or (630) 7349267. Fax: (630) 655-0391. [email protected]. . WEBSITES

Williams, Charles A., M.D., Amy C. Lossie, Ph.D., and Daniel J. Driscoll, Ph.D. “Angelman Syndrome.” (November 21, 2000). GeneClinics. University of Washington, Seattle. .

Jennifer Ann Roggenbuck, MS, CGC Rosalyn Carson-DeWitt, MD

❙ Angiography Definition

Angiography is the x-ray (radiographic) study of the blood vessels. An angiogram uses a radiopaque substance, or contrast medium, to make the blood vessels visible under x ray. The key ingredient in most radiographic contrast media is iodine.

Purpose Angiography is used to detect abnormalities, including narrowing (stenosis) or blockages in the blood vessels (called occlusions) throughout the circulatory system and in some organs. The procedure is commonly used to identify atherosclerosis; to diagnose heart disease; to evaluate kidney function and detect kidney cysts or tumors; to map renal anatomy in transplant donors; to detect an aneurysm (an abnormal bulge of an artery that can rupture leading to hemorrhage), tumor, blood clot, or arteriovenous malformations (abnormal tangles of arteries and veins) in the brain; and to diagnose problems with the retina of the eye. It is also used to provide surgeons with an accurate vascular map of the heart prior to open-heart surgery, or of the brain prior to neurosurgery. Angiography may be used after penetrating trauma, like a gunshot or knife wound, to detect blood vessel injury. It may also be used to check the position of shunts and stents placed by physicians into blood vessels.

Precautions Patients with kidney disease or injury may have further kidney damage from the contrast media used for angiography. Patients who have blood-clotting problems, have a known allergy to contrast media, or are allergic to 56

iodine may not be suitable candidates for an angiography procedure. Newer types of contrast media classified as non-ionic are less toxic and cause fewer side effects than traditional ionic agents. Because x rays carry risks of ionizing radiation exposure to the fetus, pregnant women are also advised to avoid this procedure.

Description Angiography requires the injection of a contrast medium that makes the blood vessels visible to x ray. The contrast medium is injected through a procedure known as arterial puncture. The puncture is usually made in the groin area, armpit, inside of the elbow, or neck. Patients undergoing an angiogram are advised to stop eating and drinking eight hours prior to the procedure. They must remove all jewelry before the procedure and change into a hospital gown. If the arterial puncture is to be made in the armpit or groin area, shaving may be required. A sedative may be administered to relax the patient for the procedure. An intravenous (IV) line is also inserted into a vein in the patient’s arm before the procedure begins, in case medication or blood products are required during the angiogram, or if complications arise. Prior to the angiographic procedure, patients are briefed on the details of the test, the benefits and risks, and the possible complications involved, and asked to sign an informed consent form. The site is cleaned with an antiseptic agent and injected with a local anesthetic. Then, a small incision is made in the skin to help the needle pass. A needle containing a solid inner core called a stylet is inserted through the incision and into the artery. When the radiologist has punctured the artery with the needle, the stylet is removed and replaced with another long wire called a guide wire. It is normal for blood to spurt out of the needle before the guide wire is inserted. The guide wire is fed through the outer needle into the artery to the area that requires angiographic study. A fluoroscope displays a view of the patient’s vascular system and is used to direct the guide wire to the correct location. Once it is in position, the needle is then removed, and a catheter is threaded over the length of the guide wire until it reaches the area of study. The guide wire is then removed, and the catheter is left in place in preparation for the injection of the contrast medium. Depending on the type of angiographic procedure being performed, the contrast medium is either injected by hand with a syringe or is mechanically injected with an automatic injector, sometimes called a power injector, connected to the catheter. An automatic injector is used frequently because it is able to deliver a large volume of contrast medium very quickly to the angiographic site. Usually a small test injection is made by hand to confirm

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Angiography

A female patient undergoing a cerebral angiography. The arteries of her brain are seen in the angiograms (arterial x rays) on the monitors at the upper left; a radio-opaque dye has been injected into her arterial system. (© Laurent. Photo Researchers. Reproduced by permission.)

that the catheter is in the correct position. The patient is told that the injection will start, and is instructed to remain very still. The injection causes some mild to moderate discomfort. Possible side effects or reactions include headache, dizziness, irregular heartbeat, nausea, warmth, burning sensation, and chest pain, but they usually last only momentarily. To view the area of study from different angles or perspectives, the patient may be asked to change positions several times, and subsequent contrast medium injections may be administered. During any injection, the patient or the imaging equipment may move. Throughout the injection procedure, radiographs (xray pictures) or fluoroscopic images are obtained. Because of the high pressure of arterial blood flow, the contrast medium dissipates through the patient’s system quickly and becomes diluted, so images must be obtained in rapid succession. One or more automatic film changers may be used to capture the required radiographic images. In many

imaging departments, angiographic images are captured digitally, negating the need for film changers. The ability to capture digital images also makes it possible to manipulate the information electronically, allowing for a procedure known as digital subtraction angiography (DSA). Because every image captured is comprised of tiny picture elements called pixels, computers can be used to manipulate the information in ways that enhance diagnostic information. One common approach is to electronically remove or (subtract) bony structures that otherwise would be superimposed over the vessels being studied, hence the name digital subtraction angiography. Once the x rays are complete, the catheter is slowly and carefully removed from the patient. Manual pressure is applied to the site with a sandbag or other weight for 10–20 minutes to allow for clotting to take place and the arterial puncture to reseal itself. A pressure bandage is then applied, usually for 24 hours.

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Key Terms Arteriosclerosis A chronic condition characterized by thickening and hardening of the arteries and the build-up of plaque on the arterial walls. Arteriosclerosis can slow or impair blood circulation.

Fluoroscope An imaging device that displays x rays of the body. Fluoroscopy allows the radiologist to visualize the guide wire and catheter moving through the patient’s artery.

Carotid artery An artery located in the neck that supplies blood to the brain.

Guide wire A wire that is inserted into an artery to guide a catheter to a certain location in the body.

Catheter A long, thin, flexible tube used in angiography to inject contrast material into the arteries. Cirrhosis A condition characterized by the destruction of healthy liver tissue. A cirrhotic liver is scarred and cannot function properly (i.e., breaks down the proteins in the bloodstream). Cirrhosis is associated with portal hypertension. Embolism A blood clot, air bubble, or clot of foreign material that travels and blocks the flow of blood in an artery. When blood supply blocks a tissue or organ with an embolism, infarction (death of the tissue the artery feeds) occurs. Without immediate and appropriate treatment, an embolism can be fatal. Femoral artery An artery located in the groin area that is the most frequently accessed site for arterial puncture in angiography. Fluorescein dye An orange dye used to illuminate the blood vessels of the retina in fluorescein angiography.

Most angiograms follow the general procedures outlined above, but vary slightly depending on the area of the vascular system being studied. There is a variety of common angiographic procedures. Cerebral angiography Cerebral angiography is used to detect aneurysms, stenosis, blood clots, and other vascular irregularities in the brain. The catheter is inserted into the femoral or carotid artery and the injected contrast medium travels through the blood vessels in the brain. Patients frequently experience headache, warmth, or a burning sensation in the head or neck during the injection portion of the procedure. A cerebral angiogram takes two to four hours to complete. Coronary angiography Coronary angiography is administered by a cardiologist with training in radiology or, occasionally, by a radiologist. The arterial puncture is typically made in the femoral artery, and the cardiologist uses a guide wire and catheter to perform a contrast injection and x-ray series on 58

Ischemia A lack of normal blood supply to a organ or body part because of blockages or constriction of the blood vessels. Necrosis Cellular or tissue death; skin necrosis may be caused by multiple, consecutive doses of radiation from fluoroscopic or x-ray procedures. Plaque Fatty material that is deposited on the inside of the arterial wall. Portal hypertension A condition caused by cirrhosis of the liver, characterized by impaired or reversed blood flow from the portal vein to the liver. The resulting pressure can cause an enlarged spleen and dilated, bleeding veins in the esophagus and stomach. Portal vein thrombosis The development of a blood clot in the vein that brings blood into the liver. Untreated portal vein thrombosis causes portal hypertension.

the coronary arteries. The catheter may also be placed in the left ventricle to examine the mitral and aortic valves of the heart. If the cardiologist requires a view of the right ventricle of the heart or of the tricuspid or pulmonic valves, the catheter is inserted through a large vein and guided into the right ventricle. The catheter also serves the purpose of monitoring blood pressures in these different locations inside the heart. The angiographic procedure takes several hours, depending on the complexity of the procedure. Pulmonary (lung) angiography Pulmonary, or lung, angiography is performed to evaluate blood circulation to the lungs. It is also considered the most accurate diagnostic test for detecting a pulmonary embolism. The procedure differs from cerebral and coronary angiography in that the guide wire and catheter are inserted into a vein instead of an artery, and are guided up through the chambers of the heart and into the pulmonary artery. Throughout the procedure, the patient’s vital signs are monitored to ensure that the catheter doesn’t cause arrhythmias, or irregular heartbeats. The

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thrombosis and to assess the patency and location of the vascular system prior to liver transplantation.

Kidney (renal) angiography Patients with chronic renal disease or injury can suffer further damage to their kidneys from the contrast medium used in a renal angiogram, yet they often require the test to evaluate kidney function. These patients should be well hydrated with an intravenous saline drip before the procedure, and may benefit from available medications (e.g., dopamine) that help to protect the kidney from further injury associated with contrast agents. During a renal angiogram, the guide wire and catheter are inserted into the femoral artery in the groin area and advanced through the abdominal aorta, the main artery in the abdomen, and into the renal arteries. The procedure takes approximately one hour.

Computerized tomographic angiography (CTA), a new technique, is used in the evaluation of patients with intracranial aneurysms. CTA is particularly useful in delineating the relationship of vascular lesions with bony anatomy close to the skull base. While such lesions can be demonstrated with standard angiography, it often requires studying several projections of the two-dimensional films rendered with standard angiography. CTA is ideal for more anatomically complex skull-base lesions because it clearly demonstrates the exact relationship of the bony anatomy with the vascular pathology. This is not possible using standard angiographic techniques. Once the information has been captured a workstation is used to process and reconstruct images. The approach yields shaded surface displays of the actual vascular anatomy that are three dimensional and clearly show the relationship of the bony anatomy with the vascular pathology.

Fluorescein angiography Fluorescein angiography is used to diagnose retinal problems and circulatory disorders. It is typically conducted as an outpatient procedure. The patient’s pupils are dilated with eye drops and he or she rests the chin and forehead against a bracing apparatus to keep it still. Sodium fluorescein dye is then injected with a syringe into a vein in the patient’s arm. The dye travels through the patient’s body and into the blood vessels of the eye. The procedure does not require x rays. Instead, a rapid series of close-up photographs of the patient’s eyes are taken, one set immediately after the dye is injected, and a second set approximately 20 minutes later once the dye has moved through the patient’s vascular system. The entire procedure takes up to one hour. Celiac and mesenteric angiography Celiac and mesenteric angiography involves radiographic exploration of the celiac and mesenteric arteries, arterial branches of the abdominal aorta that supply blood to the abdomen and digestive system. The test is commonly used to detect aneurysm, thrombosis, and signs of ischemia in the celiac and mesenteric arteries, and to locate the source of gastrointestinal bleeding. It is also used in the diagnosis of a number of conditions, including portal hypertension, and cirrhosis. The procedure can take up to three hours, depending on the number of blood vessels studied. Splenoportography A splenoportograph is a variation of an angiogram that involves the injection of contrast medium directly into the spleen to view the splenic and portal veins. It is used to diagnose blockages in the splenic vein and portal-vein

Most angiographic procedures are typically paid for by major medical insurance. Patients should check with their individual insurance plans to determine their coverage.

Angiography can also be performed using magnetic resonance imaging (MRI) scanners. The technique is called MRA (magnetic resonance angiography). A contrast medium is not usually used, but may be used in some body applications. The active ingredient in the contrast medium used for MRA is one of the rare earth elements, gadolinium. The contrast agent is injected into an arm vein, and images are acquired with careful attention being paid to the timing of the injection and selection of MRI specific imaging parameters. Once the information has been captured, a workstation is used to process and reconstruct the images. The post-processing capabilities associated with CTA and MRA yield three-dimensional representations of the vascular pathology being studied and can also be used to either enhance or subtract adjacent anatomical structures.

Aftercare Because life-threatening internal bleeding is a possible complication of an arterial puncture, an overnight stay in the hospital is sometimes recommended following an angiographic procedure, particularly with cerebral and coronary angiography. If the procedure is performed on an outpatient basis, the patient is typically kept under close observation for a period of six to 12 hours before being released. If the arterial puncture was performed in the femoral artery, the patient is instructed to keep his or her leg straight and relatively immobile during the observation period. The patient’s blood pressure and vital signs are monitored, and the puncture site observed closely. Pain medication may be prescribed if the patient is experiencing discomfort from the

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contrast medium is then injected into the pulmonary artery where it circulates through the lungs’ capillaries. The test typically takes up to 90 minutes and carries more risk than other angiography procedures.

Angiography

puncture, and a cold pack is often applied to the site to reduce swelling. It is normal for the puncture site to be sore and bruised for several weeks. The patient may also develop a hematoma at the puncture site, a hard mass created by the blood vessels broken during the procedure. Hematomas should be watched carefully, as they may indicate continued bleeding of the arterial puncture site.

Results The results of an angiogram or arteriogram depend on the artery or organ system being examined. Generally, test results should display a normal and unimpeded flow of blood through the vascular system. Fluorescein angiography should result in no leakage of fluorescein dye through the retinal blood vessels.

Angiography patients are also advised to have two to three days of rest after the procedure in order to avoid placing any undue stress on the arterial puncture site. Patients who experience continued bleeding or abnormal swelling of the puncture site, sudden dizziness, or chest pain in the days following an angiographic procedure should seek medical attention immediately.

Abnormal results of an angiogram may display a narrowed blood vessel with decreased arterial blood flow (ischemia) or an irregular arrangement or location of blood vessels. The results of an angiogram vary widely by the type of procedure performed, and should be interpreted by and explained to the patient by a trained radiologist.

Patients undergoing a fluorescein angiography should not drive or expose their eyes to direct sunlight for 12 hours following the procedure.

Resources

Risks Because angiography involves puncturing an artery, internal bleeding or hemorrhage are possible complications of the test. As with any invasive procedure, infection of the puncture site or bloodstream is also a risk, but this is rare. A stroke or heart attack may be triggered by an angiogram if blood clots or plaque on the inside of the arterial wall are dislodged by the catheter and form a blockage in the blood vessels or artery, or if the vessel undergoes temporary narrowing or spasm from irritation by the catheter. The heart may also become irritated by the movement of the catheter through its chambers during pulmonary and coronary angiographic procedures, and arrhythmias may develop. Patients who develop an allergic reaction to the contrast medium used in angiography may experience a variety of symptoms, including swelling, difficulty breathing, heart failure, or a sudden drop in blood pressure. If the patient is aware of the allergy before the test is administered, certain medications (e.g., steroids) can be administered at that time to counteract the reaction. Angiography involves minor exposure to radiation through the x rays and fluoroscopic guidance used in the procedure. Unless the patient is pregnant, or multiple radiological or fluoroscopic studies are required, the dose of radiation incurred during a single procedure poses little risk. However, multiple studies requiring fluoroscopic exposure that are conducted in a short time period have been known to cause skin necrosis in some individuals. This risk can be minimized by careful monitoring and documentation of cumulative radiation doses administered to these patients, particularly in those who have therapeutic procedures performed along with the diagnostic angiography. 60

BOOKS

Baum, Stanley, and Michael J. Pentecost, eds. Abrams’ Angiography, 4th ed. Philadelphia: Lippincott-Raven, 1996. LaBergem, Jeanne, ed. Interventional Radiology Essentials, 1st ed. Philadelphia: Lippincott Williams & Wilkins, 2000. Ziessman, Harvey, ed. The Radiologic Clinics of North America, Update on Nuclear Medicine. Philadelphia: W. B. Saunders Company, 2001. OTHER

Food and Drug Administration. Public Health Advisory: Avoidance of Serious X-Ray-Induced Skin Injuries to Patients during Fluoroscopically Guided Procedures. September 30, 1994. Rockville, MD: Center for Devices and Radiological Health, FDA, 1994. Radiological Society of North America CMEJ. Renal MR Angiography. April 1, 1999 (February 18, 2004). .

Stephen John Hage, AAAS, RT(R), FAHRA Lee Alan Shratter, MD

Angiomatosis see von Hippel-Lindau disease

❙ Anosmia Definition

The term anosmia means lack of the sense of smell. It may also refer to a decreased sense of smell. Ageusia, a companion word, refers to a lack of taste sensation. Patients who actually have anosmia may complain wrongly of ageusia, although they retain the ability to distinguish salt, sweet, sour, and bitter—humans’ only taste sensations.

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Of the five senses, smell ranks fourth in importance for humans, although it is much more pronounced in other animals. Bloodhounds, for example, can smell an odor that is a thousand times weaker than one perceptible by humans. Taste, considered the fifth sense, is mostly the smell of food in the mouth. The sense of smell originates from the first cranial nerves (the olfactory nerves), which sit at the base of the brain’s frontal lobes, right behind the eyes and above the nose. Inhaled airborne chemicals stimulate these nerves. There are other aberrations of smell beside a decrease. Smells can be distorted, intensified, or hallucinated. These changes usually indicate a malfunction of the brain.

Causes and symptoms The most common cause of anosmia is nasal occlusion caused by rhinitis (inflammation of the nasal membranes). If no air gets to the olfactory nerves, smell will not happen. In turn, rhinitis and nasal polyps (growths on nasal membranes) are caused by irritants such as allergens, infections, cigarette smoke, and other air pollutants. Tumors such as nasal polyps can also block the nasal passages and the olfactory nerves and cause anosmia. Head injury or, rarely, certain viral infections can damage or destroy the olfactory nerves.

Diagnosis It is difficult to measure a loss of smell, and no one complains of loss of smell in just one nostril. So a physician usually begins by testing each nostril separately with a common, non-irritating odor such as perfume, lemon, vanilla, or coffee. Polyps and rhinitis are obvious causal agents a physician looks for. Imaging studies of the head may be necessary in order to detect brain injury, sinus infection, or tumor.

Treatment Cessation of smoking is one step. Many smokers who quit discover new tastes so enthusiastically that they immediately gain weight. Attention to reducing exposure to other nasal irritants and treatment of respiratory allergies or chronic upper respiratory infections will be beneficial. Corticosteroids are particularly helpful.

Key Terms Allergen Any substance that irritates only those who are sensitive (allergic) to it. Corticosteroids Cortisone, prednisone, and related drugs that reduce inflammation. Rhinitis Inflammation and swelling of the nasal membranes. Nasal polyps Drop-shaped overgrowths of the nasal membranes.

the body heals. If chronic rhinitis is present, this is often related to an environmental irritant or to food allergies. Removal of the causative factors is the first step to healing. Nasal steams with essential oils offer relief of the blockage and tonification of the membranes. Blockages can sometimes be resolved through naso-specific therapy—a way of realigning the nasal cavities. Polyp blockage can be addressed through botanical medicine treatment as well as hydrotherapy. Olfactory nerve damage may not be regenerable. Some olfactory aberrations, like intensified sense of smell, can be resolved using homeopathic medicine.

Prognosis If nasal inflammation is the cause of anosmia, the chances of recovery are excellent. However, if nerve damage is the cause of the problem, the recovery of smell is much more difficult. Resources BOOKS

Bennett, J. Claude, and Fred Plum, eds. Cecil Textbook of Medicine. Philadelphia: W. B. Saunders Co., 1996. Harrison’s Principles of Internal Medicine. Ed. Anthony S. Fauci, et al. New York: McGraw-Hill, 1997. “Olfactory Dysfunction.” In Current Medical Diagnosis and Treatment, 1996. 35th ed. Ed. Stephen McPhee, et al. Stamford: Appleton & Lange, 1995. PERIODICALS

Davidson, T. M., C. Murphy, and A. A. Jalowayski. “Smell Impairment. Can It Be Reversed?” Postgraduate Medicine 98 (July 1995): 107-109, 112.

Alternative treatment Finding and treating the cause of the loss of smell is the first approach in naturopathic medicine. If rhinitis is the cause, treating acute rhinitis with herbal mast cell stabilizers and herbal decongestants can offer some relief as

J. Ricker Polsdorfer, MD

Anoxia see Hypoxia

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Anosmia

Description

Anticholinergics

❙ Anticholinergics

Key Terms

Definition

Anticholinergics are a class of medications that inhibit parasympathetic nerve impulses by selectively blocking the binding of the neurotransmitter acetylcholine to its receptor in nerve cells. The nerve fibers of the parasympathetic system are responsible for the involuntary movements of smooth muscles present in the gastrointestinal tract, urinary tract, lungs, etc. Anticholinergics are divided into three categories in accordance with their specific targets in the central and/or peripheral nervous system: antimuscarinic agents, ganglionic blockers, and neuromuscular blockers.

Purpose Anticholinergic drugs are used to treat a variety of disorders such as gastrointestinal cramps, urinary bladder spasm, asthma, motion sickness, muscular spasms, poisoning with certain toxic compounds, and as an aid to anesthesia.

Description Antimuscarinic agents are so called because they block muscarine, a poisonous substance found in the Amanita muscaria, a nonedible mushroom species. Muscarine is a toxic compound that competes with acetylcholine for the same cholinoreceptors. Antimuscarinic agents are atropine, scopolamine, and ipratropium bromide. Atropine and scopolamine are alkaloids naturally occurring in Atropa belladonna and Datura stramonium plants, whereas ipratropium bromide is a derivative of atropine used to treat asthma. Under the form of atropine sulfate, atropine is used in the treatment of gastrointestinal and bladder spasm, cardiac arrhythmias, and poisoning by cholinergic toxins such as organophosphates or muscarine. Atropine is used in ophthalmology as well when the measurement of eye refractive errors (i.e., cyclopegia) is required, due to its papillary dilation properties. Scopolamine shows an effect in the peripheral nervous system similar to those of atropine. However, scopolamine is a central nervous system (CNS) depressant and constitutes a highly effective treatment to prevent motion sickness, although at high doses it causes CNS excitement with side effects similar to those caused by high doses of atropine. Its use in ophthalmology is identical in purpose to that of atropine. The main use of ipratropium is for asthma treatment. Ipratropium is also administered to patients with chronic obstructive pulmonary disease. Benapryzine, benzhexol, orphenadrine, and bornaprine are other examples of anticholinergic drugs used 62

Acetylcholine The neurotransmitter, or chemical that works in the brain to transmit nerve signals, involved in regulating muscles, memory, mood, and sleep. Neuromuscular junction The junction between a nerve fiber and the muscle it supplies. Neurotransmitter Chemicals that allow the movement of information from one neuron across the gap between the adjacent neuron. Parasympathetic nervous system A branch of the autonomic nervous system that tends to induce secretion, increase the tone and contraction of smooth muscle, and cause dilation of blood vessels.

alone or in combination with other medications in Parkinson’s disease to improve motor function. Disturbances in dopaminergic transmissions are associated with the symptoms observed in Parkinson’s disease. The beneficial effects of anticholinergics in this disease are due to the resulting imbalance between dopamine and acetylcholine ratio in neurons (e.g., levels of acetylcholine lower than dopamine levels). These anticholinergic agents may interfere with mood and also decrease gastrointestinal movements, causing constipation; and the positive effects on motor functions vary among patients. Other classes of drugs available today that act on the pathways of dopamine and its receptors to treat Parkinson’s disease, such as levodopa, tolcapone, and pramipexol, effectively increase the levels of dopamine at dopaminergic receptors in neurons. Ganglionic blockers are anticholinergic agents that target nicotinic receptors in nerve cells of either sympathetic or parasympathetic systems. The most used ganglionic blockers are trimethaphan and mecamylamine. Trimethaphan is administered by intravenous infusion for the emergency short-term control of extreme high blood pressure caused by pulmonary edema, or in surgeries that require a controlled lower blood pressure, such as the repair of an aortic aneurysm. Mecamylamine is used to treat moderately severe and severe hypertension (high blood pressure), as the drug is easily absorbed when taken orally. Neuromuscular anticholinergic agents act on motornerve cholinoreceptors. They prevent the transmission of signals from motor nerves to neuromuscular structures of the skeletal muscle. Neuromuscular blockers are very useful as muscle relaxants in several surgical procedures, either as an adjuvant to anesthesia or as a pre-anesthetic. Their main therapeutic use is in surgical procedures. Examples of the first group are mivacurium, tubocurarine,

GALE ENCYCLOPEDIA OF NEUROLOGICAL DISORDERS

2004). .

Sandra Galeotti, MS

Precautions Atropine should be avoided by persons suffering from hepatitis, glaucoma, gastrointestinal obstruction, decreased liver or kidney function, and allergy to anticholinergic agents. Scopolamine is not indicated in cases of glaucoma, asthma, severe colitis, genitourinary or gastrointestinal obstruction, and myasthenia gravis, as well as people with hypersensitivity to cholinergic blockers. The prescription of ganglionic blockers to patients with kidney insufficiency, or coronary or cerebrovascular disorders requires special caution and should only be a choice when other agents cannot be used instead.

Side effects Atropine may cause severe adverse effects with dosedependent degrees of severity. Overdoses of atropine, for instance, may induce delirium, hallucinations, coma, circulatory and respiratory collapse, and death. Rapid heart rate, dilation of pupils and blurred vision, restlessness, burning pain in the throat, marked mouth dryness, and urinary retention are observed with higher doses, while lower dosages may result in decreased salivary, respiratory, and perspiration secretions. Sometimes surgeons administer atropine prior to surgery due to this antisecretory property. Scopolamine’s main side effects are similar to those observed with atropine. The adverse effects of ganglionic blockers include paralysis of gastrointestinal movements, nausea, gastritis, urinary retention, and blurred vision. Neuromuscular blockers’ adverse effects may include apnea (failure in breathing) due to paralysis of the diaphragm, hypotension (low blood pressure), tachycardia, post-surgery muscle pain, increased intraocular pressure, and malignant hyperthermia (uncontrolled high fever). Resources BOOKS

Champe, Pamela C., and Richard A. Harvey (eds). Pharmacology, 2nd ed. Philadelphia: Lippincott Williams & Wilkins, 2000. OTHER

“Anticholinergics/Antispasmodics (Systemic).” Yahoo! Health Drug Index. May 14, 2004 (May 22, 2004). . “Anticholinergics/Antispasmodics (Systemic).” Medline Plus. National Library of Medicine. May 15, 2004 (May 22,

❙ Anticonvulsants Definition

Anticonvulsants are a class of drugs indicated for the treatment of various types of seizures associated with seizure disorders such as epilepsy, a neurological dysfunction in which excessive surges of electrical energy are emitted in the brain, and other disorders. Some anticonvulsants are indicated for other medical uses. Some hydantoins, such as phenytoin, are also used as skeletal muscle relaxants and antineuralgics in the treatment of neurogenic pain. Some anticonvulsants and antiepileptic drugs (AEDs) are used in psychiatry for the treatment of bipolar disorders (manic-depression).

Purpose Although there is no cure for the disorder, anticonvulsants are often effective in controlling the seizures associated with epilepsy. The precise mechanisms by which many anticonvulsants work are unknown, and different sub-classes of anticonvulsants are thought to exert their therapeutic effects in diverse ways. Some anticonvulsants are thought to generally depress central nervous system (CNS) function. Others, such as GABA inhibitors, are thought to target specific neurochemical processes, suppress excess neuron function, and regulate electrochemical signals in the brain.

Description There are several sub-classes and types of anticonvulsants. They are marketed in the United States under a variety of brand names. • Barbiturates, including Mephobarbital (Mebaral), Pentobarbital (Nembutal), and Phenobarbital (Luminol, Solfoton). • Benzodiazepines, including Chlorazepate (Tranxene), Clonazepam (Klonopin), and Diazepam (Valium). • GABA Analogues, including Gabapentin (Neurontin) and Tiagabine (Gabitril). • Hydantoins, including Ethotoin (Peganone), Fosphentyoin (Mesantoin), and Phenytoin (Dilantin). • Oxazolidinediones, including Trimethadione (Tridione). • Phenyltriazines, including Lamotrigine (Lamictal).

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metocurine, doxacurium, and atracurium; the second group consists of rocuronium, vecuronium, pipercuronion, and pancuronium.

Anticonvulsants

time each day enables consistent levels of the medication to be maintained in the bloodstream, and results in more effective seizure control.

Key Terms Bipolar disorder A psychiatric disorder marked by alternating episodes of mania and depression. Also called bipolar illness, manic-depressive illness. Epilepsy A disorder associated with disturbed electrical discharges in the central nervous system that cause seizures. Neurogenic pain Pain originating in the nerves or nervous tissue and following the pathway of a nerve. Seizure A convulsion, or uncontrolled discharge of nerve cells that may spread to other cells throughout the brain, resulting in abnormal body movements or behaviors.

• Succinamides, including Ethosuximide (Zarontin), Methsuximide (Celontin), and Phensuximide (Milontin). • Other anticonvulsants, including Acetazolamide (Diamox), Carbamazepine (Carbatrol, Tegretol), Felbamate (Felbatol), Levetiracetam (Keppra), Oxcarbazepine (Trileptal), Primidone (Mysoline), Topiramate (Topamax), Valproic acid (Depakene, Depakote), and Zonisamide (Zonegran). A physician prescribes anticonvulsant medication, or a combination of anticonvulsant medications, according to seizure type and pattern in individual patients. Some anticonvulsant medications are not appropriate for pediatric patients under 16 years of age.

Recommended dosage Anticonvulsants are available in oral suspension (syrup), injectable, capsule, tablet, and sprinkle forms, depending on the type of medication. Not all anticonvulsants will be available in all forms. Anticonvulsants are prescribed by physicians in varying daily dosages, depending on the age, weight, and other health concerns of the individual patient, as well as the severity and frequency of their seizures. It is important to follow the prescribing physicians directions carefully as each individual anticonvulsant medication has its own recommended daily dosages and dose schedule. Some anticonvulsants are taken in a single daily dose; others are taken in divided, multiple daily doses. A double dose of any anticonvulsant medication should not be taken. If a dose is missed, it should be taken as soon as possible. However, if it is within four hours of the next scheduled dose, the missed dose should be skipped. Taking an anticonvulsant at regular intervals and at the same 64

In general, initiating any course of treatment which includes anticonvulsants requires a gradual dose-increasing regimen. Adults and children typically take a smaller daily dose for the first two weeks. Daily dosages of anticonvulsant medication may then be slowly titrated, or increased over time until adequate seizure control is achieved using the lowest dose possible. When ending a course of treatment of anticonvulsant, physicians typically taper the patient’s daily dose over a period of several weeks. Suddenly stopping treatment including anticonvulsants may cause seizures to return or occur with greater frequency. Patients taking anticonvulsants drugs for the treatment of pain or bipolar disorders may experience also have seizures, even if they have never had them before, if they suddenly stop taking the medication.

Precautions Each anticonvulsant medication may have its own precautions, counter-indications, and side-effects. However, many are common to all anticonvulsant medications. Consult the prescribing physician before taking any anticonvulsant with non-perscription medications. Patients should avoid alcohol and CNS depressants (medications that make one drowsy or tired, such as antihistimines, sleep medications, and some pain medications) while taking anticonvulants. Anticonvulsants can exacerbate the side effects of alcohol and other medications. Alcohol may also increase the risk or frequency of seizures. Anticonvulsants may not be suitable for persons with a history of stroke, anemia, thyroid, liver, depressed kidney function, diabetes mellitus, severe gastro-intestional disorders, porphyria, lupus, some forms of mental illness, high blood presure, angina (chest pain), irregular heartbeats, and other heart problems. Before beginning treatment with anticonvulsants, patients should notify their physician if they consume a large amount of alcohol, have a history of drug use, are nursing, pregnant, or plan to become pregnant. Physicians generally advise the use of effective birth control while taking many anticonvulsant medications. Patients taking anticonvulsants should be aware that many anticonvulsants may increase the risk of birth defects. Furthermore, many anticonvulsant medications are secreted in breast milk. Patients who become pregnant while taking any anticonvulsant should contact their physician immediately to discuss the risks and benefits of continuing treatment during pregnancy and while nursing.

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Side effects In some patients, anticonvulsants may produce usually mild side effects. Headache, nausea, and unusual tiredness and weakness are the most frequently reported side effects of anticonvulsants. Other general side effects of anticonvulsants that do not usually require medical attention include:

• depression or suicidal thoughts • mood or mental changes, including excessive fear, anxiety, hostility • severe tremors • prolonged numbness in the extremeties • general loss of motor skills • persistent lack of appetite • altered vision • frequent or burning urination • difficulty breathing • chest pain or irregular heartbeat

• mild coordination problems

• faintness or loss of consciousness

• mild dizziness

• persistant, severe headaches

• abdominal pain or cramping

• persistant fever or pain.

• sinus pain

Interactions

• sleeplessness or nightmares • change in appetite • mild feelings of anxiety • feeling of warmth • tingling or prickly feeing on the skin, or in the toes and fingers • mild tremors • diarrhea or constipation • heartburn or indigestion • aching joints and muscles or chills • unpleasant taste in mouth or dry mouth Many of these side effects disappear or occur less frequently during treatment as the body adjusts to the medication. However, if any symptoms persist or become too uncomfortable, the perscribing physician should be consulted. Other, uncommon side effects of anticonvulsants can be serious or may indicate an allergic reaction. A patient taking any anticonvulsant who experiencs one or more of the following symptoms should contact the prescribing physician immediately: • rash or bluish, purplish, or white patches on the skin • jaundice (yellowing of the skin and eyes) • bloody nose or unusual bleeding • hallucinations (seeing visions or hearing voices that are not present) • sores in the mouth or around the eyes • ringing or vibrations in the ears

Anticonvulsants may have negative interactions with some antacids, anticoagulants, antihistimines, antidepressants, antibiotics, pain killers (including lidocaine) and monoamine oxidase inhibitors (MAOIs). Other medications such as amiodarone, diazoxide, phenybutazone, sulfonamides (sulfa drugs), corticosteroids, sucralfate, rifampin, and warfarin may also adversely react with anticonvulsants. Some anticonvulsants should not be used in combination with other anticonvulsants. (For example, phenytoin (a hydantoin) when used with valproic acid, another anticonvulsant, may increase the seizure frequency). However, several anticonvulsant medications are indicated to be used in conjunction with or suppliment other anticonvulsants. If advised and carefully monitored by a physician, a course of treatment including multiple seizure prevention medications can be effective and safe. Most anticonvulsants decrease the effectiveness of contraceptives that contain estrogens or progestins, including oral contraceptives (birth control pills), progesterone implants (Norplant), and progesterone injections (Depo-Provera). Resources BOOKS

Masters, Roger D., Michael T. McGuire. The Neurotransmitter Revolution. Southern Illinois University Press, 1994. Mondimore, Francis Mark. Bipolar Disorder: A Guide for Patients and Families. Baltimore: The Johns Hopkins University Press, 1999. Weaver, Donald F. Epilepsy and Seizures: Everything You Need to Know. Firefly Books, 2001.

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Some anticonvulsants may be prescribed for children. However, children may experience increased side effects. Research indicates that some children who take high doses of some anticonvulsants (such as hydantoins) for an extended period of time may experience mild learning difficulties or not perform as well in school.

Antiepileptic drugs

Key Terms Absence seizures Also called a petit mal seizure, characterized by abrupt, short-term lack of conscious activity or other abnormal change in behavior.

Partial seizure An episode of abnormal activity in a localized, specific part of the brain that causes changes in attention, movement, and/or behavior.

Atonic seizure A seizure characterized by a sudden loss of muscle tone, causing the individual to fall to the floor.

Status epilepticus A serious condition involving continuous seizures with no conscious intervals.

Epilepsy A disorder associated with disturbed electrical discharges in the central nervous system that cause seizures.

Tonic-clonic seizure A seizure involving the entire body characterized by unconsciousness, muscle contraction, and rigidity. Also called grand mal or generalized seizures.

Febrile convulsion Seizures occurring mainly in children between three months and five years of age that are triggered by fever.

Description

Wyllie, Elaine. The Treatment of Epilepsy: Principles and Practice. New York: Lippincott, Williams & Wilkins, 2001. PERIODICALS

Feely, Morgan. “Drug treatment of epilepsy.” BMJ 318 (9 January 1999): 106–109. “Risk of birth defects with anticonvulsants evaluated.” Psychopharmacology Update 12, no. 5 (May 2001): 3. OTHER

“Seizure Medicines.” Epilepsy.com. (May 1, 2004). ORGANIZATIONS

Epilepsy Foundation. 4351 Garden City Drive, Landover, MD 20785-7223. (800) 332-1000. . American Epilepsy Society. 342 North Main Street, West Hartford, CT 06117-2507. .

Adrienne Wilmoth Lerner

❙ Antiepileptic drugs Definition

Antiepileptic drugs are all drugs used to treat or prevent convulsions, as in epilepsy.

Purpose Antiepileptic drugs (AEDs) are designed to modify the structures and processes involved in the development of a seizure, including neurons, ion channels, receptors, glia, and inhibitory or excitatory synapses. These processes are modified to favor inhibition over excitation in order to stop or prevent seizure activity. 66

Trigeminal neuralgia A disorder of the trigeminal nerve that causes severe facial pain.

The ideal AED would suppress all seizures without causing any unwanted side effects. Unfortunately, the drugs currently used not only fail to control seizure activity in some patients, but frequently cause side effects that range in severity from minimal impairment of the central nervous system (CNS) to death from aplastic anemia or liver (hepatic) failure. Prior to 1993, the choice of an antiepileptic medication was limited to traditional drugs, as phenobarbital, primidone, phenytoin, carbamazepine and valproate. Although these drugs have the advantage of proven efficacy (effectiveness), many patients are left with refractory (break-through) seizures. Since 1993, many new medications have been approved by the United States Food and Drug Administration (FDA), expanding treatment options. The newer AEDs offer the potential advantages of fewer drug interactions, unique mechanisms of action, and a broader spectrum of activity. The AEDs can be grouped according to their main mechanism of action, although many have several different actions and others work through unknown mechanisms. The main groups include sodium channel blockers, calcium current inhibitors, gamma-aminobutyric acid (GABA) enhancers, glutamate blockers, and drugs with unknown mechanisms of action. Sodium Channel Blockade Blocking the sodium channel in the cell membrane is the most common and the most well-characterized mechanism of currently available AEDs. AEDs that target these sodium channels prevent the return of the channels to the active state by stabilizing the inactive form. In doing so, repetitive firing of nerve impulses from the axon of the nerve is prevented. The blockade of sodium channels of

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Calcium Current Inhibitors Calcium channels are small channels in the nerve cell that function as the “pacemakers” of normal rhythmic brain cell activity. Calcium current inhibitors are particularly useful for controlling absence seizures. The drug ethosuximide is a calcium current inhibitor.

GABA Reuptake Inhibitors GABA reuptake inhibitors boost the levels of GABA, a neurotransmitter, in the brain. Neurotransmitters such as GABA are naturally occurring chemicals that transmit messages from one neuron (nerve cell) to another. When one neuron releases GABA, it normally binds to the next neuron, transmitting information and preventing the transmission of extra electrical activity. When levels of GABA are reduced, there may not be enough GABA to sufficiently bond to the neuron, leading to extra electrical activity in the brain and seizures. Tiagabine works to block GABA from being re-absorbed too quickly into the tissues, thereby increasing the amount available to bind to neurons.

GABA Receptor Agonist GABA receptor agonists bind with certain cell-surface proteins and produce changes that mimic that action of GABA, thereby reducing excess electrical activity and seizures. Clonazepam, phenobarbital, and primidone are examples of GABA receptor agonist drugs. Some drugs such as valproate enhance the synthesis of GABA, in addition to other potential mechanisms of action, and thus prevent seizures. Glutamate Blockers Glutamate and aspartate are the two most important excitatory neurotransmitters in the brain. By blocking glutamate action, the excess electrical activity that causes seizures is controlled. Topiramate and felbamate are examples of glutamate blocker drugs, but their use is limited because they sometimes produce hallucinations and behavior changes.

Recommended dosage Antiepileptic drugs are usually prescribed in an initial dose, then gradually increased over time until maximum seizure control is achieved with a minimum of side effects. Recommended dosages for specific antiepileptic drugs include:

• Carbamazepine: In generalized tonic-clonic seizures or partial seizures, by mouth, ADULT: initially 100 mg twice daily, increased gradually according to response to usual maintenance dose of 0.8–1.2 g; ELDERLY: reduce initial dose; CHILD: 10–20 mg/kg daily in divided doses. Trigeminal neuralgia, by mouth, ADULT: initially 100 mg 1–2 times daily increased gradually according to response; usual dose 200 mg 3–4 times daily with up to 1.6 g daily. • Clonazepam: Epilepsy, by mouth, ADULT: initially 1 mg at night for 4 nights, increased gradually over 2–4 weeks to a usual maintenance dose of 4–8 mg daily in divided doses; ELDERLY: initial dose 500 micrograms increased as above; CHILD: up to 1 year initially 250 micrograms increased as above to 0.5–1 mg daily in divided doses; 1–5 years: initially 250 micrograms increased to 1–3 mg daily in divided doses; 5–12 years: initially 500 micrograms increased to 3–6 mg daily in divided doses. • Diazepam: Emergency management of recurrent epileptic seizures, by slow intravenous injection (at rate of 5 mg/minute), ADULT: 10–20 mg, repeated if necessary after 30–60 minutes; may be followed by intravenous infusion to maximum 3 mg/kg over 24 hours; CHILD: 200 to 300 micrograms/kg (or 1 mg per year of age); by rectum as solution, ADULT and CHILD over 10 kg: 500 micrograms/kg; ELDERLY: 250 micrograms/kg; repeated if necessary every 12 hours. Febrile convulsions, by rectum as solution; CHILD over 10 kg: 500 micrograms/kg (maximum 10 mg), with dose repeated if necessary. Seizures associated with poisoning, by slow intravenous injection (at rate of 5 mg/minute), ADULT: 10–20 mg. • Ethosuximide: Absence seizures, by mouth, ADULT and CHILD over 6 years: initially 500 mg daily, increased by 250 mg at intervals of 4–7 days to a usual dose of 1–1.5 g daily (occasionally, up to maximum of 2 g daily); CHILD under 6 years: initially 250 mg daily, increased gradually to usual dose of 20 mg/kg daily. • Felbamate: By mouth, ADULT: 2400–4600 mg per day; CHILD: 40–60 mg/kg per day. Optimal individual maintenance doses will be determined by clinical response. • Fosphenytoin: For emergency management of repeated seizures, by intravenous injection, 22.5 to 30 mg per kg. For nonemergent therapy, by intravenous injection, 15 to 30 mg per kg, followed by 6 to 12 mg per kg for maintenance therapy. • Lamotrigine: ADULT: by mouth, if added to valproate monotherapy, 25 mg daily for two weeks, then 50 mg daily for two weeks, then titrate up to 150 mg twice daily. If added to carbamazepine, phenytoin, phenobarbital, or primidone, initial dose 50 mg twice daily, subsequent increases up to 100–200 mg twice daily.

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nerve axons causes stabilization of the neuronal membranes and limits the development of seizure activity. Sodium channel blocker drugs include: carbamazepine, phenytoin, fosphenytoin, oxcarbazepine, lamotrignine, and zonizamide.

Antiepileptic drugs

CHILD, by mouth, if added to valproate monotherapy, initial dose 0.5 mg/kg/day, final maintenance dose of 1–5 mg/kg/day. If added to carbamazepine, phenytoin, phenobarbital, or primidone: initial doses 2 mg/kg/day, with subsequent increases to 5–15 mg/kg/day. • Levetiracetam: ADULT: by mouth, 1000–3000 mg/day. CHILD: dosage range not established. • Oxcarbazepine: ADULT: by mouth, 600–2400 mg per day; CHILD: by mouth, 10–30 mg/kg per day. • Phenobarbital: Generalized tonic-clonic seizures, partial seizures, by mouth, ADULT: 60-180 mg at night; CHILD: up to 8 mg/kg daily. Febrile convulsions, by mouth, CHILD: up to 8 mg/kg daily. Neonatal seizures, by intravenous injection (dilute injection 1 in 10 with water for injections), NEWBORN: 5–10 mg/kg every 20–30 minutes up to plasma concentration of 40 mg/liter. By intravenous injection (dilute injection 1 in 10 with water for injections), ADULT: 10 mg/kg at a rate of not more than 100 mg/minute (up to maximum total dose of 1 g); CHILD: 5–10 mg/kg at a rate of not more than 30 mg/minute. • Phenytoin sodium: Generalized tonic-clonic seizures, partial seizures, by mouth, ADULT: initially 3–4 mg/kg daily (as a single dose or in 2 divided doses), increased gradually by 25 mg at intervals of 2 weeks as necessary (with plasma-phenytoin concentration monitoring); usual dose 200–500 mg daily; CHILD: initially 5 mg/kg daily in 2 divided doses; usual dose range 4–8 mg/kg daily (maximum 300 mg). • Primidone: ADULT: by mouth, 500–1250 mg per day. CHILD: by mouth, 5–20 mg/kg per day. Optimal individual maintenance doses will be determined by clinical response. • Sodium valproate: Generalized tonic-clonic seizures, partial seizures, absence seizures, atonic seizures; myoclonic seizures, by mouth, ADULT: initially 600 mg daily in 2 divided doses, preferably after food, increased by 200 mg daily at 3-day intervals to maximum of 2.5 g daily in divided doses; usual maintenance dose 1–2 g daily (20–30 mg/kg daily); CHILD: up to 20 kg, initially 20 mg/kg daily in divided doses, may be increased provided plasma concentrations monitored; CHILD over 20 kg: initially 400 mg daily in divided doses, increased until control (usually in range of 20–30 mg/kg daily); maximum 35 mg/kg daily. • Tiagabine: By mouth, suggested ADULT maintenance dose 32 to 56 mg/day. Dosage titrations of 4–8 mg/day weekly are suggested by the manufacturer. • Topiramate: ADULT: by mouth, 400 mg per day. An initiation schedule, where the medication dose is increased 68

by 50 mg/day each week, is recommended to reduce adverse effects; slower rates of initiation are used by some physicians. • Zonisamide: ADULT: by mouth, 100–400 mg/day; CHILD dosage range not established.

Precautions Withdrawal Treatment is normally continued for a minimum of two years after the last seizure. Withdrawal should be extended over a period of several months, as abrupt withdrawal can lead to complications such as status epilepticus, a serious event where seizures occur rapidly and continuously. Many adult patients relapse once treatment is withdrawn and it may be justified to continue treatment indefinitely, particularly when the patient’s livelihood or lifestyle can be endangered by recurrence of a seizure. Pregnancy and Breast-feeding Untreated epilepsy during pregnancy may cause harm to the fetus; there is, therefore, no justification for abrupt withdrawal of treatment. Withdrawal of therapy with antiepileptic medications may be an option if the patient has been seizure-free for at least two years. Resumption of treatment may be considered after the first trimester. If antiepileptics are continued in pregnancy, a single medication with the lowest effective dose is preferred, and blood levels of the medication should be monitored. There is an increased risk of birth defects with the use of AEDs, particularly carbamazepine, valproate, and phenytoin. However, if there is good seizure control, many physicians see no advantage in changing pregnant patients’AEDs. In view of the risks of neural tube and other defects, patients who may become pregnant should be informed of the risks and referred for advice, and pregnant patients should be offered counseling and screening. To counteract the risk of neural tube defects, adequate folic acid supplements are advised for women before and during pregnancy. In view of the risk of bleeding associated with carbamazepine, phenobarbital, and phenytoin, prophylactic phytomenadione (vitamin K1) is recommended for the mother before delivery and the newborn. Use of AEDs can often be continued during breastfeeding.

Driving Regulations are in place in many countries that may restrict driving by patients with epilepsy. Further, AEDs may cause central nervous system depression, particularly in the early stages of treatment. Patients affected by adverse effects such as drowsiness or dizziness should not operate machinery or drive.

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The most common side effects of therapy with antiepileptic drugs are drowsiness and dizziness. Other drug-specific side effects include: • Carbamazepine: Dizziness, double vision, nausea, loss of coordination, and blurred vision. • Clonazepam: Sedation, ataxia (loss of coordination), hyperactivity, restlessness, irritability, depression, cardiovascular or respiratory depression. Children and infants may have excess saliva production. Occasionally, tonic seizures may be exacerbated. • Diazepam: Drowsiness, dizziness, tiredness, weakness, dry mouth, diarrhea, upset stomach, changes in appetite, restlessness or excitement, constipation, difficulty urinating, frequent urination, blurred vision, changes in sex drive or ability. • Ethosuximide: Drowsiness, upset stomach, vomiting, constipation, diarrhea, stomach pain, loss of taste and appetite, weight loss, irritability, mental confusion, depression, insomnia, nervousness, and headache. • Felbamate: Insomnia, weight loss, nausea, decreased appetite, dizziness, fatigue, ataxia (loss of coordination), and lethargy. • Fosphenytoin: Burning/tingling sensations, groin pain, itching, nausea, dizziness or drowsiness may occur. Serious side effects may occur: mental/mood changes, loss of coordination, rash, eye/vision problems. • Lamotrigine: Rash is the main concern associated with this drug. Other commonly reported adverse reactions are headache, blood dyscrasias, ataxia (loss of coordination), double vision, psychosis, tremor, hypersensitivity reactions, and prolonged sleepiness or insomnia. • Levetiracetam: Sleepiness, asthenia (loss of strength), dizziness, accidental injury, convulsion, infection, pain, pharyngitis, and a flu-like syndrome. • Oxcarbazepine: Sleepiness, headache, dizziness, rash, low blood sodium level, weight gain, and hair loss. • Phenobarbital: Thought and behavior alterations, sedation, psychomotor slowing, poor concentration, depression, irritability, ataxia (loss of coordination), and decreased libido. • Phenytoin sodium: Ataxia (loss of coordination), abnormal rapid eye movements, drowsiness and lethargy, nausea and vomiting, rash, blood disorders, headaches, vitamin K and folate deficiencies, loss of libido, hormonal dysfunction, and bone marrow suppression. • Primidone: Intense sedation, dizziness, and nausea at the onset of treatment. • Sodium valproate: Nausea, vomiting, tremor, sedation, confusion or irritability, and weight gain, elevated blood sugar levels, and hair loss or curling of hair.

• Tiagabine: Dizziness, fatigue, depression, confusion, impaired concentration, speech or language problems, lack of energy, weakness, upset stomach, nervousness, tremor, and stomach pain. • Topiramate: Dizziness, sleepiness, ataxia (loss of coordination), confusion, fatigue, decreased sensation in lower extremities, speech difficulties, double vision, impaired concentration, and nausea. • Zonizamide: Dizziness, anorexia, headache, ataxia (loss of coordination), confusion, speech abnormalities, mental slowing, irritability, tremor, weight gain, excessive sleepiness, and fatigue.

Interactions Antiepilectic drugs may be prescribed alone or in combination with other antiepileptic drugs. In general, drugs that cause central nervous system depression, including alcohol, should be used with caution by those taking antiepileptic medications. Many antiepileptic medications also reduce the effectiveness of oral contraceptives (birth control pills). Specific drug interventions include: • Carbamazepine: Several drugs, such as macrolide antibiotics (erythromycin and clarithromycin), isoniazid, chloramphenicol, calcium channel blockers, cimetidine, and propoxyphene, inhibit liver enzyme function responsible for the metabolic breakdown of carbamazepine, thereby raising its levels in the blood. Phenobarbital, phenytoin, felbamate, and primidone decrease efficiency of carbamazepine. Toxic symptoms or breakthrough seizures may occur if the dose of carbamazepine is not adjusted. Grapefruit juice and St. John’s wort can increase carbamazepine levels. Carbamazepine reduces the effectiveness of tricyclic antidepressants, oral contraceptives, cyclosporin A, and warfarin. • Clonazepam: Clonazepam blood levels are decreased by coadministration of enzyme-inducing drugs. No significant clinical interactions have been reported. • Diazepam: Diazepam may increase the effects of other drugs that cause drowsiness, including antidepressants, alcohol, antihistamines, sedatives, pain relievers, anxiety medicines, seizure medicines, and muscle relaxants. Antacids may decrease the effects of diazepam. • Ethosuximide: Ethosuximide may increase the amount of other antiseizure medications in the blood. Such medications include phenytoin, mephenytoin, and ethotoin. These drugs must be monitored if they are used with ethosuximide to prevent the occurrence of dangerous side effects. Ethosuximide may decrease the level of primidone in the blood, which could lead to a loss of

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Side effects

Antiepileptic drugs

seizure control. Valproic acid may increase or decrease ethosuximide levels and must be used with caution.

an adjustment of the carbamazepine dosage may also be necessary.

• Felbamate: Felbamate increases blood levels of phenytoin. Adjustments in dosage may be necessary. Its levels are increased by carbamazepine. Felbamate also increases levels of valproic acid in blood.

• Sodium valproate: Increases plasma levels of free fractions of phenytoin sodium, phenobarbital, carbamazepine epoxide, and lamotrigine. It decreases total phenytoin sodium level. The levels of sodium valproate are decreased by enzyme-inducing drugs and are increased by felbamate and clobazam.

• Fosphenytoin: Fosphenytoin has no specific known interactions. • Lamotrigine: Levels increase with concomitant use of valproate. • Levetiracetam: No significant drug interactions have been identified. • Oxcarbazepine: Interacts with oral contraceptives, thereby reducing their efficacy. • Phenobarbital: Metabolism of phenobarbital is inhibited by phenytoin sodium, valproate, felbamate, and dextropropoxyphene. Enzyme inducers, such as rifampicin, decrease phenobarbital levels. Because of the potent induction of liver enzymes, phenobarbital increases the metabolism of estrogen, steroids, warfarin, carbamazepine, diazepam, clonazepam, and valproate. • Phenytoin sodium: Among all AEDs, phenytoin sodium has one of the most problematic drug interaction profiles. Carbamazepine and phenobarbital have variable and unpredictable effects (i.e., increase or decrease) on phenytoin sodium levels. Valproate raises levels of phenytoin sodium by displacing phenytoin sodium from its proteinbinding site and inhibiting its metabolism. Other drugs that significantly increase phenytoin sodium levels are isoniazid, cimetidine, chloramphenicol, dicumarol, and sulfonamides. Drugs that lower phenytoin sodium levels are vigabatrin and amiodarone. Phenytoin sodium itself is a strong inducer of liver enzymes and alters levels of other drugs. It decreases levels of carbamazepine, ethosuximide, felbamate, primidone, tiagabine, and phenobarbital. It inhibits dicumarol, warfarin, and corticosteroids; clotting factors and immunosuppression must be monitored and doses adjusted accordingly. Other drugs whose levels are reduced by phenytoin sodium and require monitoring and adjustment include furosemide, cyclosporin, folate, and praziquantel. Levels of chloramphenicol and quinidine are elevated by phenytoin sodium. • Primidone: Primidone interacts with most other AEDs. Acetazolamide, carbamazepine, ethosuximide, and methsuximide may all decrease the effects of primidone, and larger primidone doses may be necessary. Phenytoin, ethotoin, mephenytoin, and isoniazid may increase blood levels of primidone, and an adjustment of primidone dosage may be necessary. Carbamazepine blood levels may be higher during therapy with primidone, and 70

• Tiagabine: Causes a small decrease in valproate levels. Hepatic-inducing drugs increase the clearance of tiagabine by two thirds. Drug plasma concentrations are not affected by valproate, cimetidine, or erythromycin. • Topiramate: Enzyme-inducing drugs, such as phenytoin sodium or carbamazepine, decrease topiramate concentrations in the blood by approximately 50%. Topiramate generally does not affect the steady-state concentrations of the other drugs given in polytherapy, although phenytoin sodium levels may rise occasionally. Topiramate reduces ethyl estradiol levels by 30% and may inactivate the low-dose contraceptive pill. It may cause a mild reduction in digoxin levels. • Zonisamide: Phenytoin sodium, carbamazepine, phenobarbital, and valproic acid reduce levels of zonizamide in the blood; however, zonizamide does not affect the levels of these drugs. Resources BOOKS

Hardman, Joel Greiffith, Lee E. Limbird, and Alfred G. Gilman. Goodman & Gilman’s The Pharmacological Basis of Therapeutics. New York: McGraw-Hill Professional, 2001. PERIODICALS

LaRoche, S., and S. Helmers. “The New Antiepileptic Drugs.” JAMA 291 (2004): 605–614. OTHER

“Antiepileptic Drugs: An Overview.” eMedicine.

(April 26, 2004). “Seizure Medicines.” Epilepsy.com. (April 26, 2004). ORGANIZATIONS

The Epilepsy Foundation. 4351 Garden City Drive, Landover, MD 20785-7223. (800) 332-1000. or .

Sandra Galeotti

❙ Carotid endarterectomy Definition

Carotid endarterectomy is a surgical procedure to treat obstruction of the carotid artery caused by atherosclerotic plaque formation.

Purpose The purpose of surgical therapy for vascular disease is to prevent stroke. Stroke can be caused by atherosclerosis of the carotid arteries located in the neck. Atherosclerosis is a degenerative disease of the cardiovascular system, which can occur in the carotid arteries in the neck, resulting in plaques of lipids, cholesterol crystals, and necrotic cells. The plaques in the carotid arteries can result in disease by embolizing, thrombosing, or causing stenosis (narrowing of artery). The plaques in the carotid arteries can cause disease if they obstruct a vessel or get dislodged and obstruct another area.

Precautions The procedure is contraindicated in patients with an occluded carotid artery and in cases of severe neurologic deficit resulting from cerebral infarction. Additionally, the procedure is not performed in persons with concurrent medical illness severe enough to limit life expectancy. During the operation, precautions should be taken to prevent intraoperation movement of the atherosclerotic plaque. This can occur by excessive manipulation of the carotid bifurcation (the anatomical point where the internal and external carotid is joined together). The internal carotid will extend from the neck and penetrate the brain (to provide the brain with blood), whereas the external carotid will form other smaller arteries to provide blood to structures within the neck region. Atherosclerotic plaques are fragile especially if they are ulcerated. During the operation the surgeon must carefully dissect free other attached vessels such as the common carotid, internal carotid, and external carotid arteries with minimal physical manipulation of the affected carotid vessel.

Description The first successful carotid endarterectomy was performed by DeBakey in 1953. During the past 40 years the procedure has been optimized and has become the most 188

frequently performed peripheral vascular operation in the United States. There are more than 130,000 cases of carotid endarterectomy performed annually in the United States. Several randomized prospective clinical trials have conclusively established both the safety and efficacy of carotid endarterectomy and its superiority for favorable outcomes when compared to the best medical management. Largely due to credible scientific and clinical research, there has been a very large increase in the performance of this procedure over the past ten years. It is understandable that the procedure is common since it is utilized for the treatment of stroke, which is a condition that is associated with high morbidity (death rates) and is frequent. Carotid endarterectomy is the most common surgical procedure in the United States utilized to treat stenosis (narrowing) of the carotid artery. There are approximately more than 700,000 incident strokes annually and 4.4 million stroke survivors. There are 150,000 annual deaths from stroke. Approximately 30% of stroke survivors die within the first 12 months. Within 12 years approximately 66% will eventually die from stroke, making this condition the third leading cause of death in the United States. The cause of atherosclerosis is unknown, but injury to the arteries can occur from infectious agents, hyperlipidemia, cigarette smoking, and hypertension. The aggregate cost associated with approximately 400,000 first strokes in 1990 was $40.6 billion. Among those who have experienced one stroke, the incidence of stroke within five years is 40–50%. Research as of 2002 concludes that carotid endarterectomy remains the standard of care for the treatment of carotid artery atherosclerosis.

Surgical Description A vertical incision is made in front of the sternocleidomastoid muscle providing optimal exposure of the surgical field. The line of the incision (10 cm in length) begins at the mastoid process and extends to approximately one to two fingerbreadths above the sternal notch. The exact location of carotid bifurcation can be determined before operation by ultrasound studies or arteriography. Muscles and nerves within the area are carefully displaced to allow access to the diseased area (plaque). When the surgical field is cleared of adjacent anatomical structures the endarterectomy portion of the procedure is carried out. This is accomplished by an incision in the common carotid artery at the site below the atherosclerotic plaque. The surgeon then uses an angled scissor (called a Potts scissor) to incise the common carotid artery through the plaque into the normal internal carotid artery. It is vital to extend the arterial incision (arteriotomy) above and below the atherosclerotic plaque. The surgeon utilizes a blunt dissecting instrument called a Penfield instrument to dissect the atherosclerotic plaque from the attachment to the arterial wall.

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After removing the atherosclerotic plaque, primary closure with sutures, or closure with a vein or prosthetic patch, is performed. Research indicates that utilization of a prosthetic patch is more favorable than suture closing. During this stage of the operation flushing is important to remove debris and air. Vein patch is advantageous because this type of closure reduces the risk of thrombus accumulation and possibly prevents perioperative stroke.

Preparation As part of the preoperative preparation, routine laboratory tests for blood chemistry (complete blood count, electrolytes), kidney function tests, lipid profiles, and special blood tests to monitor clotting times are ordered by the clinician. Measurement of clotting times is important because blood thinner medications are typically given to patients preoperatively. Neuroimaging studies of the head are important in symptomatic patients to identify old or new cerebral infarcts. Carotid ultrasound studies are the screening test of choice accepted by surgeons to evaluate for carotid stenosis. An electrocardiogram (ECG) is important for evaluating past myocardial infarction and ischemic cardiac changes. The importance of ECG monitoring cannot be overemphasized given that the most common cause of postoperative mortality (death) is cardiac arrest. Positioning of the patient is also important. The operating table should be horizontal without head elevation. The head should be partially turned to the opposite side of the surgical field. It may be advantageous to place a rolled towel under the patient’s shoulders to exaggerate neck extension. Gentle preparation and cleaning of operative fields should ensure minimal physical manipulation and pressure to avoid dislodging fragments of atherosclerotic plaque. The goals for anesthetic management include control of blood pressure and heart rate, protection of the brain and heart from ischemic insult, and relief of surgical pain and operative stress responses. Routine monitors (ECG and pulse oximetry to measure blood oxygen levels) and oxygen face mask are placed prior to anesthetic induction. Typically, any commonly utilized anesthetic and muscle relaxants (nondepolarizing) can be administered for carotid endarterectomy.

Aftercare Aspirin therapy should be initiated at the time of diagnosis of transient ischemic attack (TIA), amaurosis fugax (transient visual loss), or stroke. Recent research from the prospective Aspirin and Carotid Endarterectomy (ACE) trial suggests that low dose (80 to 325 mg per day) of aspirin is optimal in preventing thromboembolic events after carotid endarterectomy. After carotid endarterectomy

the patient’s blood should be tested (complete blood count and electrolytes). Cardiac function can be monitored with ECG recordings. Frequent neurologic assessment is essential as well as hemodynamic monitoring (with the goal of maintaining blood pressure at its prior range). The patient should be observed for hemotoma formation which could cause airway obstruction. Antiplatelet therapy is necessary. About two weeks postoperatively patients are evaluated for neurologic and wound complications. Carotid ultrasound studies are performed after six months postoperatively and annually scheduled.

Risks There are several important complications that can occur after carotid endarterectomy. Stroke or transient neurologic deficit can occur within 12 to 24 hours after operation. These conditions are usually caused by thromboembolic complications, which typically originate from the endarterectomy site or damaged vessels that were involved during the operative procedure (internal, common, and external carotid arteries). In approximately 33–50% of patients, hypertension or hypotension can occur. Wound complications such as hemotoma formation can cause pain and tracheal (wind pipe) deviation, which can impair normal breathing. During surgery, damage to vital nerves can occur, such as cervical nerves which supply sensation to the neck region. Patients may complain of numbness in the lower ear, lower neck, and upper face regions. Damage to the hypoglossal nerve (which provides innervations of the tongue), can produce deviation of the tongue to the paralyzed side and speech impairment. Additionally, the problem can reoccur, resulting in stenosis and symptoms.

Normal results The normal progression of results following carotid endarterectomy is the prevention of stroke which is approximately 1.6% (two-year stroke risk), compared to 12.2% for patients who are medically treated. The results of the Asymptomatic Carotid Atherosclerosis Study (ACAS) reveal that the incidence of stroke for the postsurgical group (those receiving carotid endarterectomy) was 5.1%; for the group treated medically, the incidence was 11%. As with all surgical procedures, it is important for patients to select a surgeon who has expertise in the particular procedure and in the management of the condition. Some studies indicate that surgeons should perform 10 to 12 carotid endarterectomies every year in order to maintain surgical expertise and management skills. Resources BOOKS

Miller, Ronald D., et al, eds. Anesthesia. 5th ed. Churchill Living Stone, Inc. 2000.

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Arterial Reconstruction

Carotid endarterectomy Carotid endarterectomy. (Custom Medical Stock Photo. Reproduced by permission.)

Key Terms Atherosclerotic plaque A deposit of fatty and calcium substances that accumulate in the lining of the artery wall, restricting blood flow. Cerebral infarction Brain tissue damage caused by interrupted flow of oxygen to the brain. Electrolytes Salts and minerals that produce electrically charged particles (ions) in body fluids. Common human electrolytes are sodium chloride, potassium, calcium, and sodium bicarbonate. Electrolytes control the fluid balance of the body and are important in muscle contraction, energy generation, and almost all major biochemical reactions in the body. Hyperlipidemia A condition characterized by abnormally high levels of lipids in blood plasma. Hypertension Abnormally high arterial blood pressure that if left untreated can lead to heart disease and stroke. Mastoid process The protrusions of bone behind the ears at the base of the skull.

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Myocardial infarction Commonly known as a heart attack, a myocardial infarction is an episode in which some of the heart’s blood supply is severely cut off or restricted, causing the heart muscle to suffer and die from lack of oxygen. Sternocleidomastoid muscle A muscle located in front of the neck that functions to turn the head from side to side. Stroke Interruption of blood flow to a part of the brain with consequent brain damage. A stroke may be caused by a blood clot or by hemorrhage due to a burst blood vessel. Also known as a cerebrovascular accident. Transient ischemic attack A brief interruption of the blood supply to part of the brain that causes a temporary impairment of vision, speech, or movement. Usually, the episode lasts for just a few moments, but it may be a warning sign for a full-scale stroke.

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PERIODICALS

Barnett, Henry J. M. “The appropriate use of carotid endarterectomy.” Canadian Medical Association Journal 166 (April 2002): 9. Gross, Cary, P. “Relation between prepublication release of clinical trial results and the practice of carotid endarterectomy.” Journal of the American Medical Association 284 (December 2000): 22. Mullenix, Philip. “Carotid Endarterectomy remains the gold standard.” American Journal of Surgery 183, no. 59 (May 2002). Perler, Bruce A. “Carotid Endarterectomy: The ‘gold standard’ in the endovascular era.” Journal of the American College of Surgeons 194, no. 1 (January 2002). Walker, Paul M. “Carotid Endarterectomy: applying trial results in clinical practice.” Canadian Medical Association Journal 157 (1997). ORGANIZATIONS

National Stroke Association. 9707 E. Easter Lane, Englewood, Colarado 80112. 303-649-9299 or 1-800-strokes; Fax: 303-649-1328. .

Laith Farid Gulli, M.D. Robert Ramirez, D.O.

❙ Carotid stenosis Definition

Carotid stenosis is the medical description of the narrowing or constriction of the carotid artery. The artery is located in the neck, and the narrowing of the artery is caused by the buildup of plaque (fatty deposits). The process of atherosclerosis causes a hardening of the walls of the arteries and, in the case of atherosclerosis in the carotid artery, results in a carotid stenosis that reduces the flow of blood and nutrients to the brain.

Description

blood flow. This blockage interrupts the supply of nutrients and oxygen to the brain, and is one of the causes of cerebral vascular accidents, known as stroke. Carotid stenosis is a form of cerebral vascular disease and atherosclerosis.

Demographics Stroke is the third leading cause of death in the United States after coronary artery disease and cancer, with approximately 750,000 strokes and more than 150,000 deaths occurring each year in the United States. Approximately 50% of these strokes are thought to be the result of carotid stenosis.

Causes and symptoms The cause of carotid stenosis is the buildup of plaque on the inner wall of the carotid artery. The reduced blood flow to the brain and the blockage of other arteries following the release of emboli can cause a stroke. Increased risk of carotid stenosis is associated with smoking, hypertension, elevated levels of cholesterol, obesity, and a sedentary lifestyle. Some of these factors such as hypertension and cholesterol level may also be related to a person’s physiology. Another risk factor is diabetes. Older, less active people are more prone to carotid stenosis. Additionally, the older a person is, the greater the risk posed by carotid stenosis. Sometimes, prior to a major stroke, a person can be temporarily affected by the arterial blockage or release of a small embolus. The interrupted flow of blood to the brain, which can be very brief or last a few hours, does not persist longer than 24 hours. Symptoms of this transient event, called a transient ischemic attack (TIA), include weakness, as well as visual and speech difficulties. The exact symptoms of carotid stenosis depend on the area of the brain that is affected. Symptoms can also be absent, with the stenosis discovered only incidentally during a clinical examination. In the event of a stroke, if the blocked blood flow is not restored, brain cells can die, causing permanent brain damage.

The carotid arteries run up the sides of the neck. They are vital arteries, and are a route of blood to the anterior part of the brain and, via branches, to the eyes, forehead, and nose. The deposition of plaque along the inner wall of an artery narrows its diameter. This makes the clogged artery less efficient in transporting blood. Plaque formation can become so severe that an artery is effectively blocked.

Although not as accurate as other methods, a physician can listen to the pulsing of blood through the carotid artery by means of a stethoscope. The weaker pulse that is a result of stenosis will be evident in the form of altered sounds (bruits) as the blood flows past the area of disturbance.

Carotid stenosis poses another danger when bits of the plaque dislodge. These pieces, which are referred to as blood clots or emboli, can move upward with the flow of blood towards the brain and can become lodged, blocking

Sometimes, carotid stenosis is suspected if a person has a transient malfunction of blood flow to the brain, or a TIA. A TIA can last anywhere from a few seconds to several hours. The temporary blockage of the artery can

Diagnosis

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Townsend, Courtney M. Sabiston Textbook of Surgery. 16th ed. W. B. Saunders Company, 2001.

Carotid stenosis

Key Terms Carotid endarterectomy Surgical procedure designed to reduce the accumulation of plaque in the carotid artery and thus prevent stroke. Cerebral vascular accident Damage to brain cells caused by lack of blood flow in the brain from emboli (clots) plaque, or hemorrhage. Stenosis Narrowing or constriction of a blood vessel or passage in the body.

The third technique is known as an angiogram or arteriogram. An angiogram is an examination that utilizes x rays after a small tube (catheter) is inserted into the base of the carotid artery. An x-ray dye is then injected. The dye reveals the areas of the regions of the artery that are narrowed or blocked.

Treatment team Diagnosis and treatment of carotid stenosis involves the primary care physician, nurses, neurologist, neurosurgeons, neuroradiologists, and specialists who are skilled in performing angioplasty.

Treatment False-color angiogram showing stenosis in the carotid artery. (Photograph by Alfred Pasteka. (c) CNRI/ Science Photo Library, National Audubon Society Collection/Photo Researchers, Inc. Reproduced by permission.)

Carotid stenosis is treated surgically or medically. One of two surgical treatments is typically used. The first approach is known as microsurgical carotid endarterectomy. The second approach is termed endovascular angioplasty and stenting.

cause a momentary loss of vision in one eye, a weak or numb sensation on one side of the body, slurred speech, or inability to speak. A TIA can be a warning to a physician of the potential presence of carotid stenosis.

Carotid endarterectomy is the surgical exposure of the carotid artery and the removal of the plaque. This re-establishes the uninterrupted flow of blood to the brain. This approach is the method of choice for most patients. However, the technique does itself carry a risk of stroke (stroke can be caused in up to 3% of surgeries).

Three main diagnostic tests aid in the diagnosis of carotid stenosis. The first is known as a duplex sonogram, or a carotid duplex. The procedure involves the use of highfrequency sound waves (ultrasound). The ultrasonic waves echo off of the carotid artery to produce a two-dimensional image on a monitor. If narrowing or obstruction of the carotid artery is present, it is often apparent in the image. Another powerful imaging technique is magnetic resonance imaging (MRI) or magnetic resonance angiography (MRA). Both rely on the use of magnetism. Pulses of magnetic energy can be used to image the targeted area of the body, based on the interruption of the flow of the electrons in the magnetic field. This information is then converted to a visual image. 192

For patients who are unable to undergo surgery, the angioplasty and stenting approach is used. In this approach a catheter that contains an expandable region at one end is inserted into the carotid artery. The end of the catheter is then expanded. This “balloon” squeezes the plaque against the arterial wall, increasing the effective diameter of the artery. Then, a stent is placed inside the artery. A stent is a tubular arrangement of fibers somewhat similar visually to wire fencing rolled up into a tube. The stent reinforces the carotid artery to prevent its collapse and to keep the plaque tightly against the arterial wall. Surgery and the associated risks may not be warranted in patients whose arterial blockage is less than 50%.

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Resources BOOKS

Wiebers, David. Stroke-Free for Life: The Complete Guide to Stroke Prevention and Treatment. 2nd. ed. Mayo Clinic. New York: Harper Resource, 2002. PERIODICALS

Clinical trials As of February 2004, a clinical trial designed to investigate the relative effectiveness of carotid angioplasty with stenting versus carotid endarterectomy in preventing stroke, myocardial infarction, and death was recruiting patients in the United States and Canada. Participants should have symptoms of carotid stenosis. The trial, called “Carotid Revascularization Endarterectomy versus Stent Trial (CREST),” was being coordinated by the National Institute for Neurological Diseases and Stroke. Another clinical trial was designed to examine the role of diet (specifically high doses of vitamin E) on the metabolism of low-density lipoprotein, which is critical in plaque formation. This trial was being coordinated by the National Institute of Health’s National Center for Complimentary and Alternative Medicine. Information on both clinical trials may be found at the National Institute of Health Clinical Trials website: www.clinicaltrials.gov.

Prognosis With prompt medical treatment, including surgery, recovery from carotid stenosis can be complete with no residual effects. However, if treatment is delayed or if a stroke occurs, damage can be permanent. If carotid stenosis is dealt with promptly by surgery, medicine, or lifestyle modifications, prognosis is good. For example, at the Johns Hopkins Medical School, carotid stenosis corrective surgery has a mortality rate of 0.8% (80 in 1,000 people) and a morbidity rate (the person survives, but with some complication) of 1.8% (18 in 1,000 people). However, undiagnosed stenosis can result in stroke. Depending on the severity of the stroke, prognosis is variable. An estimated 325,000 strokes and 75,000 deaths occur each year in the United States due to carotid stenosis.

Special concerns Even if there are no symptoms associated with the presence of carotid stenosis, the malady is often a warning sign of possible blockage of the arteries of the heart, or coronary artery disease. Thus, people diagnosed with carotid stenosis should be carefully monitored for coronary artery disease.

Biller, J., and W. H. Thies. “When to operate in carotid artery disease.” American Family Physician (January 2000): 400–406. OTHER

Johns Hopkins Department of Neurosurgery. “What is Carotid Stenosis?” Johns Hopkins University School of Medicine. (February 1, 2004).. “Risk Reduction through Surgery: Carotid Endarterectomy.” National Stroke Association. (March 1, 2004). . Toronto Brain Vascular Malformation Study Group. “Carotid Stenosis. What is Carotid Stenosis?” University of Toronto. (February 1, 2004).. ORGANIZATIONS

American Stroke Association, a division of the American Heart Association. 7272 Greenville Avenue, Dallas, TX 75231. (888) 4-STROKE. . Centers for Disease Control and Prevention (CDC). 1600 Clifton Road, Atlanta, GA 30333. (404) 639-3311 or (800) 311-3435. . National Institute for Neurological Diseases and Stroke (NINDS). 6001 Executive Boulevard, Bethesda, MD 20892. (301) 496-5751 or (800) 352-9424. .

Brian Douglas Hoyle, PhD

❙ Carpal tunnel syndrome Definition

Carpal tunnel syndrome is an entrapment neuropathy of the wrist. It occurs when the median nerve, which runs through the wrist and enervates the thumb, pointer finger, middle finger and the thumb side of the ring finger, is aggravated because of compression. Symptoms include numbness, tingling and pain in the fingers the median nerve sensitizes. Some people have difficulty grasping items and may have pain radiating up the arm. Carpal tunnel syndrome is common in people who work on assembly lines, doing heavy lifting and packing involving repetitive motions. Other repetitive movements such as

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Anticoagulant medications such as aspirin can be used instead to reduce the tendency of blood clots to form. Treatment can also consist of lifestyle modifications such as stopping smoking, limiting cholesterol intake, or use of cholesterol-lowering medications.

Carpal tunnel syndrome

typing; are often implicated in cause carpal tunnel syndrome, however some clinical evidence contradicts this association. Additional causes of the syndrome include pregnancy, diabetes, obesity or simply wrist anatomy in which the carpal tunnel is narrow. Treatment includes immobilization with a splint or in severe cases surgery to release the compression of the median nerve.

Description Carpal tunnel syndrome (CTS) is caused by a compression of the median nerve in the wrist, a condition known as nerve entrapment. Nerve entrapments occur when a nerve that travels through a passage between bones and cartilage becomes irritated because a hard edge presses against it. In almost every case of nerve entrapment, one side of the passage is moveable and the repetitive rubbing exacerbates the injury. Three sides of the carpal tunnel are made up of three bones that form a semicircle around the back of the wrist. The fourth side of the carpal tunnel is made up of the transverse carpal tunnel ligament also called the palmar carpal ligament, which runs across the wrist on the same side as the palm. This ligament is made of tissue that cannot stretch or contract, making the cross sectional area of the carpal tunnel a fixed size. Running through the carpal tunnel are nine tendons that assist the muscles that move the hand and the median nerve. The median nerve enervates the thumb, forefinger, middle finger, and the thumb side of the ring finger. The ulnar nerve that serves the little finger side of the ring finger and the little finger runs outside of the transverse carpal tunnel ligament and is therefore less likely to become entrapped in the wrist. The tendons that run through the carpal tunnel are encased in a lubricating substance called tensynovium. This substance can become swollen when the tendons rub quickly against one another, as occurs when the finger muscles are used repeatedly. When this happens, there is less space within the carpal tunnel for the median nerve and it becomes compressed or pinched. When a nerve is compressed, the blood supply to the nerve is interrupted. In an attempt to alleviate the problem, the body’s immune system sends new cells called fibroblasts to the area to try to build new tissue. This eventually results in scar tissue around the nerve. In an area that cannot expand this only worsens the situation and puts more pressure on the nerve. A compressed nerve can be likened to an electrical wire that has been crimped. It cannot transmit electrical signals to the brain properly and the result is a feeling of numbness, tingling or pain in the areas that the nerve enervates. Compression of the median nerve causes tingling and numbness in the thumb, forefinger, middle finger and on 194

Key Terms Median nerve A nerve that runs through the wrist and into the hand. It provides sensation and some movement to the hand, the thumb, the index finger, the middle finger, and half of the ring finger. Neuropathy A disease or abnormality of the peripheral nerves (the nerves outside the brain and spinal cord). Major symptoms include weakness, numbness, paralysis, or pain in the affected area.

the thumb-side of the fourth finger. It may also cause pain in the forearm and occasionally into the shoulder. Some persons have a difficult time gripping and making a fist. People who suffer from CTS range from those who are mildly inconvenienced and must wear a splint at night to relieve pressure on the median nerve to those who are severely debilitated and lose use of their hands. Problems associated with CTS can invade a person’s life making even simple tasks such as answering the phone, reading a book or opening a door extremely difficult. In severe cases, surgery to release the median nerve is often suggested by an orthopedist. The carpal tunnel ligament is cut, relieving the pressure within the carpal tunnel. Rates of success are quite high with the surgical procedure.

Demographics Carpal tunnel syndrome is more common in women than in men, perhaps because the carpal tunnel generally has a smaller cross section in women than in men. The ratio of women to men who suffer from CTS is about three to one. CTS is most often diagnosed in people who are between 30 and 50 years old. It is more likely to occur in people whose professions require heavy lifting and repetitive movements of the hands such as manufacturing, packing, cleaning and finishing work on textiles.

Causes and symptoms Carpal tunnel syndrome may occur when anything causes the size of the carpal tunnel to decreases or when anything puts pressure on the median nerve. Often the cause is simply the result of an individual’s anatomy; some people have smaller carpal tunnels than others. Trauma or injury to the wrist, such as bone breakage or dislocation can cause CTS if the carpal tunnel is narrowed either by the new position of the bones or by associated swelling. Development of a cyst or tumor in the carpal tunnel will also result in increased pressure on the median nerve and likely CTS. Systemic problems that result in swelling may

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Much evidence suggests that one of the more common causes of CTS involves performing repetitive motions such as opening and closing of the hands or bending of the wrists or holding vibrating tools. Motions that involve weights or force are thought to be particularly damaging. For example, the types of motions that assembly line workers perform such as packing meat, poultry or fish, sewing and finishing textiles and garments, cleaning, and manufacturing are clearly associated with CTS. Other repetitive injury disorders such as data entry while working on computers are also implicated in CTS. However, some clinical data contradicts this finding. These studies show that computer use can result in bursitis and tendonitis, but not CTS. In fact, a 2001 study by the Mayo Clinic found that people who used the computer up to seven hours a day were no more likely to develop CTS than someone who did not perform the type of repetitive motions required to operate a keyboard. The two major symptoms of carpal tunnel syndrome include numbness and tingling in the thumb, forefinger, middle finger and the thumb side of the fourth finger and a dull aching pain extending from the wrist through the shoulder. The pain often worsens at night because most people sleep with flexed wrists, which puts additional pressure on the median nerve. Eventually the muscles in the hands will weaken, in particular, the thumb will tend to lose strength. In severe cases, persons suffering from CTS are unable to differentiate between hot and cold temperatures with their hands.

Diagnosis Diagnosis of carpal tunnel syndrome begins with a physical exam of the hands, wrists and arms. The physician will note any swelling or discoloration of the skin and the muscles of the hand will be tested for strength. If the patient reports symptoms in the first four fingers, but not the little finger, then CTS is indicated. Two special tests are used to reproduce symptoms of CTS: the Tinel test and the Phalen test. The Tinel test involves a physician taping on the median nerve. If the patient feels a shock or a tingling in the fingers, then he or she likely has carpal tunnel syndrome. In the Phalen test, the patient is asked to flex his or her wrists and push the backs of the hands together. If the patient feels tingling or numbness in the hands within one minute, then carpal tunnel syndrome is the likely cause.

A variety of electronic tests are used to confirm CTS. Nerve conduction velocity studies (NCV) are used to measure the speed with which an electrical signal is transferred along the nerve. If the speed is slowed relative to normal, it is likely that the nerve is compressed. Electromyography involves inserting a needle into the muscles of the hand and converting the muscle activity to electrical signals. These signals are interpreted to indicate the type and severity of damage to the median nerve. Ultrasound imaging can also be used to visualize the movement of the median nerve within the carpal tunnel. X rays can be used to detect fractures in the wrist that may be the cause of carpal tunnel syndrome. Magnetic resonance imaging (MRI) is also a useful tool for visualizing injury to the median nerve.

Treatment team Treatment for carpal tunnel syndrome usually involves a physician specializing in the bones and joints (orthopedist) or a neurologist, along with physical and occupational therapists, and if necessary, a surgeon.

Treatment Lifestyle changes are often the first type of treatment prescribed for carpal tunnel syndrome. Avoiding activities that aggravate symptoms is one of the primary ways to manage CTS. These activities include weight-bearing repetitive hand movements and holding vibrating tools. Physical or occupational therapy is also used to relieve symptoms of CTS. The therapist will usually train the patient to use exercises to reduce irritation in the carpal tunnel and instruct the patient on proper posture and wrist positions. Often a doctor or therapist will suggest that a patient wear a brace that holds the arm in a resting position, especially at night. Many people tend to sleep with their wrists flexed, which decreases the space for the median nerve within the carpal tunnel. The brace keeps the wrist in a position that maximizes the space for the nerve. Doctors may prescribe non-steroidal anti-inflammatory medications to reduce the swelling in the wrist and relieve pressure on the median nerve. Oral steroids are also useful for decreasing swelling. Some studies have shown that large quantities of vitamin B-6 can reduce symptoms of CTS, but this has not been confirmed. Injections of corticosteroids into the carpal tunnel may also be used to reduce swelling and temporarily provide some extra room for the median nerve. Surgery can be used as a final step to relieve pressure on the median nerve and relieve the symptoms of CTS. There are two major procedures in use, both of which involve cutting the transverse carpal tunnel ligament. Dividing this ligament relieves pressure on the median nerve and allows blood flow to the nerve to increase. With time,

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also cause CTS such as hypothyroidism, problems with the pituitary gland, and the hormonal imbalances that occur during pregnancy and menopause. Arthritis, especially rheumatoid arthritis, may also cause CTS. Some patients with diabetes may be more susceptible to CTS because they already suffer from nerve damage. Obesity and cigarette smoking are thought to aggravate symptoms of CTS.

Carpal tunnel syndrome Medical illustration of left wrist and hand showing carpel tunnel syndrome. The yellow lines represent the median nerve, the blue bands the tendons. Repetitive motion of the wrist and hand causes swelling, and the resulting compression of the nerve results in pain and sometimes nerve damage. (© R. Margulies. Custom Medical Stock Photo. Reproduced by permission.)

the nerve heals and as it does so, the numbness and pain in the arm are reduced. Open release surgery is the standard for severe CTS. In this procedure, a surgeon will open the skin down the front of the palm and wrist. The incision will be about two inches long stretching towards the fingers from the lowest fold line on the wrist. Then next incision is through the palmar fascia, which is a thin connective tissue layer just below the skin, but above the transverse carpal ligament. Finally, being careful to avoid the median nerve and the tendons that pass through the carpal tunnel, the surgeon carefully cuts the transverse carpal ligament. This releases pressure on the median nerve. Once the transverse carpal tunnel ligament is divided, the surgeon stitches up the palma fascia and the skin, leaving the ends of the ligament loose. Over time, the space between the ends of the ligament will be joined with scar tissue. The resulting space, which studies indicate is approximately 26% greater than prior to the surgery, is enlarged enough so that the median nerve is no longer compressed.

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A second surgical method for treatment of CTS is endoscopic carpal tunnel release. In this newer technique, a surgeon makes a very small incision below the crease of the wrist just below the carpal ligament. Some physicians will make another small incision in the palm of the hand, but the single incision technique is more commonly used. The incision just below the carpal ligament allows the surgeon to access the carpal tunnel. He or she will then insert a plastic tube with a slot along one side, called a cannula, into the carpal tunnel along the median nerve just underneath the carpal ligament. Next an endoscope, which is a small fiber-optic cable that relays images of the internal structures of the wrist to a television screen, is fed through the cannula. Using the endoscope, the surgeon checks that the nerves, blood vessels and tendons that run through the carpal tunnel are not in the way of the cannula. A specialized scalpel is fed through the cannula. This knife is equipped with a hook on the end that allows the surgeon to cut as he or she pulls the knife backward. The surgeon positions this knife so that it will divide the carpal ligament as he pulls it out of the cannula. Once the knife is pulled through the cannula, the carpal ligament is severed,

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The two different surgical techniques for treating CTS have both positive and negative attributes and the technique used depends on the individual case. In open release, the surgeon has a clear view of the anatomy of the wrist and can make sure that the division of the transverse ligament is complete. He or she can also see exactly which structures to avoid while making the incision. On the other hand, because the incision to the exterior is much larger than in endoscopic release, recovery time is usually longer. While the symptoms of CTS usually improve rapidly, the pain associated with the incision may last for several months. Many physicians feel that the recovery time associated with endoscopic release is faster than that for open release because the incision in the skin and palma fascia are so much smaller. On the other hand, endoscopic surgery is more expensive and requires training in the use of more technologic equipment. Some believe that are also risks that the carpal ligament may not be completely released and the median nerve may be damaged by the cannula, or the specialized hooked knife. Research is ongoing in an attempt to determine whether open or endoscopic release provides the safest and most successful results. Success rates of release surgery for carpal tunnel syndrome are extremely high, with a 70–90% rate of improvement in median nerve function. There are complications associated with the surgery, although they are generally rare. These include incomplete division of the carpal ligament, pain along the incisions and weakness in the hand. Both the pain and the weakness are usually temporary. Infections following surgery for CTS are reported in less than 5% of all patients.

Recovery and rehabilitation One day following surgery for carpal tunnel syndrome, a patient should begin to move his or her fingers, however gripping and pinching heavy items should be avoided for a month and a half to prevent the tendons that run through the carpal tunnel from disrupting the formation of scar tissue between the ends of the carpal ligament. After about a month and a half, a patient can begin to see an occupational or physical therapist. Exercises, massage and stretching will all be used to increase wrist strength and range of motion. Eventually, the therapist will prescribe exercises to improve the ability of the tendons

within the carpal tunnel to slide easily and to increase dexterity of the fingers. The therapist will also teach the patient techniques to avoid a recurrence of carpal tunnel syndrome in the future.

Clinical trials There are a variety of clinical trials underway that are searching for ways to prevent and treat carpal tunnel syndrome. The National Institute of Arthritis and Musculoskeletal and Skin Diseases (NIAMS) supports this research on CTS. Their website is . One trial seeks to determine which patients will benefit from surgical treatments compared to non-surgical treatments using a new magnetic resonance technique. The study is seeking patients with early, mild to moderate carpal tunnel syndrome. Contact Brook I. Martin at the University of Washington for more information. The phone number is (206) 616–0982 and the email is [email protected]. A second trial compares the effects of the medication amitriptyline, acupuncture, and placebos for treating repetitive stress disorders such as carpal tunnel syndrome. The study is located at Harvard University. For information contact Ted Kaptchuk at (617) 665–2174 or tkaptchu@ caregroup.harvard.edu. A third study is evaluating the effects of a protective brace for preventing carpal tunnel syndrome in people who use tools that vibrate in the workplace. The brace is designed to absorb the energy of the vibrations while remaining unobtrusive. For information on this study contact Prosper Benhaim at the UCLA Hand Center. The phone number is (310) 206–4468 and the email address is [email protected].

Prognosis Persons with carpal tunnel syndrome can usually expect to gain significant relief from prescribed surgery, treatments, exercises, and positioning devices. Resources BOOKS

Johansson, Phillip. Carpal Tunnel Syndrome and Other Repetitive Strain Injuries. Brookshire, TX: Enslow Publishers, Inc. 1999. Shinn, Robert, and Ruth Aleskovsky. The Repetitive Strain Injury Handbook. New York: Henry Holt and Company. 2000. OTHER

“Carpal Tunnel Syndrome.” American Association of Orthopaedic Surgeons. (February 11, 2004).

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but the palma fascia and the skin are not cut. Just as in the open release surgery, cutting the carpal ligament releases the pressure on the median nerve. Over time, scar tissue will form between the ends of the carpal ligament. After the cannula is removed from the carpal tunnel, the surgeon will stitch the small incision in patient’s wrist and the small incision in the palm if one was made.

Catechol-O-methyltransferase inhibitors

. “Carpal Tunnel Syndrome Fact Sheet.” National Instititute of Neurological Disorders and Stroke. (February 11, 2004). . ORGANIZATIONS

American Chronic Pain Association (ACPA). P.O. Box 850, Rocklin, CA 95677. (916) 632-0922 or (800) 533-3231. [email protected]. . National Chronic Pain Outreach Association (NCPOA). P.O. Box 274, Millboro, VA 24460. (540) 862-9437; Fax: (540) 862-9485. [email protected]. . National Institute of Arthritis and Musculoskeletal and Skin Dieseases (NIAMS). National Institutes of Health, Bldg. 31, Rm. 4C05, Bethesda, MD 20892. (301) 496-8188; Fax: (540) 862-9485. [email protected]. .

Juli M. Berwald, Ph.D.

❙ Catechol-O-methyltransferase inhibitors

Definition Catechol-O-methyltransferase (COMT) inhibitors are a class of medication used in combination with levodopa and carbidopa in the treatment of symptoms of Parkinson’s disease (PD). COMT inhibitors such as tolcapone and entacapone optimize the active transport of levodopa to the central nervous system (CNS) and allow the administration of lower doses of both levodopa and carbidopa, which decreases or even prevents the side effects related to these two drugs.

Purpose Levodopa is a drug that helps to supplement dopamine, a neurotransmitter, to the brain of persons with PD. A neurotransmitter is a chemical that is released during a nerve impulse that transmits information from one nerve cell to another. In PD, levels of the neurotransmitter dopamine progressively decrease as the disease evolves. Drug therapy with levodopa also leads to dopamine formation in tissues outside the brain and in the gastrointestinal tract, causing undesirable side effects and reduced availability of levodopa to the nerve cells. The addition of carbidopa to the treatment regimen inhibits this action and thus, increases levodopa uptake into the brain. However, the inhibition of dopamine results in activation of certain enzymes (including catechol-O-methyltransferase) that compete with levodopa for transport to the 198

Key Terms Ataxia Loss of muscle coordination due to nerve damage. Carbidopa A drug combined with levodopa to slow the breakdown of the levodopa, used to treat the symptoms of Parkinson’s disease. Levodopa A precursor of dopamine which is converted to dopamine in the brain, and the drug most commonly used to treat the symptoms of Parkinson’s disease.

brain. By giving drugs that reduce these enzymes, competition is reduced, and more levodopa is utilized by the brain. The administration of a COMT inhibitor drug prolongs the duration of each levodopa dose, and allows the reduction of doses of both levodopa and carbidopa by approximately 30%.

Description Tolcapone was the first COMT inhibitor approved by the United States Food and Drug Administration to be taken orally in association with the levodopa/carbidopa regimen. Tolcapone is readily absorbed through the gastrointestinal tract and has a fairly rapid action. The drug is metabolized in the liver and eliminated from the body through the feces and urine. However, its COMT inhibitory activity lasts much longer, due to the high affinity of tolcapone with the enzyme. Entacapone, another COMT inhibitor, was first approved in the European Union and its effects are similar to those obtained with tolcapone when added to levodopa/carbidopa regimen.

Recommended dosage The physician will adjust the dose of either tolcapone or entacapone to each patient in accordance with other individual clinical characteristics.

Precautions The use of tolcapone requires a reduction of levodopa/carbidopa to prevent the occurrence of levodoparelated side effects, such as low blood pressure and dizziness when rising, loss of appetite, nausea, drowsiness, and hallucinations. Patients with liver disorders or reduced liver function should not receive tolcapone due to its high toxicity to the liver cells. All patients using tolcapone should be regularly monitored by their physician and laboratory blood tests to determine the concentrations of liver

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Entacapone is metabolized in the liver and a pre-existing reduced liver function or chronic deficiency should be reported to the physician to allow for adjustments in dosage. Dosage adjustments or special precautions may be also necessary when entacapone is administered to patients under treatment with one or more of the following medications: isoproterenol, epinephrine, apomorphine, isoetherine, or bitolterol. Except for selegiline, all monoamine oxidase (MAO) inhibitors are contraindicated when using entacapone.

Side effects The more common tolcapone-related side effects are abdominal pain, nausea, vomiting, diarrhea, drowsiness, sleep disorders, headache, and dizziness, especially in the first few days of treatment. Elderly patients may have hallucinatory episodes (sensations of seeing, hearing or feeling something that does not exist). Some patients report irritability, aching joints and neck, muscle cramps, agitation, ataxia, difficulty in concentrating, and increased urination. Severe episodes of diarrhea may occur after the second month of treatment. Common side effects with entacapone are abdominal discomfort (constipation, nausea, diarrhea, abdominal pain) and fatigue, which tend to disappear as the body adapts to the medication. Some patients may experience gastritis, heartburns, belching, sleep disorders, increased perspiration, drowsiness, agitation, irritation and mood changes, and fatigue.

Interactions Patients should inform the physician of any other medication in use when tolcapone prescription is being considered. The concomitant use of entacapone and methyldopa may cause heart rhythm disturbances and abrupt changes in blood pressure. Resources BOOKS

Champe, Pamela C., and Richard A. Harvey, eds. Pharmacology, 2nd ed. Philadelphia, PA: Lippincott Williams & Wilkins, 2000.

Weiner, William J., M.D., Parkinson’s Disease: A Complete Guide for Patients and Families. Baltimore: Johns Hopkins University Press, 2001. OTHER

Hubble, Jean Pintar, M.D., Richard C. Berchou, Pharm.D. “CATECHOL-O-METHYL TRANSFERASE (COMT) INHIBITORS.” The National Parkinson Foundation, Inc. (April 25, 2004). . “Entacapone and Tolcapone.” We Move. July 25, 1999. (April 24, 2004). . ORGANIZATIONS

National Parkinson Foundation. 1501 N.W. 9th Avenue, Bob Hope Research Center, Miami, FL 33136-1494. (305) 243-6666 or (800) 327-4545; Fax: (305) 243-5595. [email protected]. .

Sandra Galeotti

Causalgia see Reflex sympathetic dystrophy Cavernous angioma see Cerebral cavernous malformation Cavernous malformation see Cerebral cavernous malformation Central cervical cord syndrome see Central cord syndrome

❙ Central cord syndrome Definition

Central cord syndrome is an “incomplete lesion,” a condition in which only part of the spinal cord is affected. In central cord syndrome, there is greater weakness or outright paralysis of the upper extremities, as compared with the lower extremities. Unlike a complete lesion, that causes loss of all sensation and movement below the level of the injury, an incomplete lesion causes only a partial loss of sensation and movement.

Description Central cord syndrome specifically affects the central part of the spinal cord, also known as the “grey matter.” The segment of spinal cord affected by central cord syndrome is the cervical segment, the part of the spinal cord that is encased within the first seven vertebrae, running from the base of the brain and into the neck. The central

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enzymes should be periodically performed. As the chronic use of tolcapone may cause irreversible liver injury, any signs of dark urine, pale stools, unusual fatigue, fever, jaundice, persistent nausea or vomiting, and tenderness in the upper right side of the abdomen should be reported to the physician. Tolcapone is contraindicated in pregnant women and during breast-feeding, or to patients already suffering from low blood pressure. Kidney deficiency reduces the elimination rate of tolcapone metabolites and increases the severity of adverse effects.

Central cord syndrome

Causes and symptoms

Key Terms Cervical Pertaining to a neck. Lesion An abnormal or injured area. Paralysis Loss of the ability to move. Spondylosis A degenerative condition of the cervical spine, causing narrowing of the bony canal through which the spinal cord passes. Stenosis Abnormal narrowing. Syringomyelia A chronic disease involving abnormal accumulations of fluid within the spinal column.

part of the cervical spinal cord is responsible for carrying information to and from the upper extremities and the brain, resulting in movement. Because the outer (peripheral) areas of the cervical spinal cord are spared, information going to and from the brain and the lower extremities is not as severely affected. The specific degree of impairment depends on the severity of the injury. More mild impairment may result in problems with fine motor control of the hands, while more severe impairment may cause actual paralysis of the upper limbs. While the lower limbs are less severely affected in central cord syndrome, in more serious injuries the lower extremities may demonstrate some degree of weakness, loss of sensation, or discoordination. Loss of bladder control may be evident as well. Central cord syndrome often strikes people who are already suffering from a degenerative spinal disease called spondylosis or spinal stenosis. In spondylosis, a progressive narrowing of the spinal canal puts increasing pressure on the spinal cord, resulting in damage and debilitation. Often, a fall or other injury that causes a person with spondylosis to extend his or her neck will cause the already-narrowed spinal canal to injure the spinal cord, resulting in central cord syndrome.

Demographics

Individuals with central cord syndrome may first notice neck pain and shooting or burning pains in the arms and hands. Tingling, numbness, and weakness may also be evident. Fine motor control of the upper extremities may be significantly impaired. Sensation in the upper limbs may be dulled or completely lost. Sensation from the legs may be lost, as well, and the lower extremities may demonstrate some degree of weakness and impaired movement. Bladder control may be weakened or lost.

Diagnosis Diagnosis is usually accomplished through imaging of the cervical spine, with plain x rays, CT scans, and/or MRI imaging.

Treatment team The treatment team for central cord syndrome will consist of a neurologist and a neurosurgeon, as well as multiple rehabilitation specialists, including physiatrists, physical therapists, and occupational therapists.

Treatment Usually, intravenous steroids are immediately administered to patients suspected of suffering from central cord syndrome, to decrease swelling and improve outcome. Surgery may be performed in certain cases, in order to stabilize the spine or in order to decompress the spinal cord.

Prognosis

As with other types of spinal cord injuries, men are more frequently affected by central cord syndrome than women. Because central cord syndrome can result from either injury or as a sequelae to the spinal disease spondylosis, there are two age peaks for the condition: in younger individuals (secondary to trauma) or in older individuals (secondary to spondylosis).

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Any injury or condition that preferentially damages the central, gray matter of the cervical spinal cord can lead to central cord syndrome. The most common causes include complications of the progressive, degenerative spinal disease called spondylosis, as well as traumatic injury to the cervical spine, such as fractures or dislocations. Injuries to a cervical spine that is already abnormally narrow due to disease is a particularly common cause of central cord syndrome. Tumors or syringomyelia (a chronic disease involving abnormal accumulations of fluid within the spinal column) may also lead to central cord syndrome.

Many patients will be able to rehabilitate their less-severely affected lower extremities and will continue walking, although sometimes with a permanently abnormal, stiff, spastic gait. Many individuals also regain some strength and function of their upper extremities. Upper extremity fine motor coordination, however, usually remains impaired.

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BOOKS

Hammerstad, John P. “Strength and Reflexes.” In Textbook of Clinical Neurology, edited by Christopher G. Goetz. Philadelphia: W. B. Saunders Company, 2003. Mercier, Lonnie R. “Spinal Cord Compression.” In Ferri’s Clinical Advisor: Instant Diagnosis and Treatment, edited by Fred F. Ferri. St. Louis: Mosby, 2004. Morris, Gabrielle, F., William R. Taylor, and Lawrence F. Marshall. “Spine and Spinal Cord Injury.” In Cecil Textbook of Internal Medicine, edited by Lee Goldman, et al. Philadelphia: W. B. Saunders Company, 2000. WEBSITES

National Institute of Neurological Disorders and Stroke (NINDS). NINDS Central Cord Syndrome Information Page. November 6, 2002. (June 4, 2004). . ORGANIZATIONS

National Spinal Cord Injury Association. 6701 Democracy Blvd. #300-9, Bethesda, MD 20817. 301-214-4006 or 800-962-9629; Fax: 301-881-9817. [email protected]. .

Rosalyn Carson-DeWitt, MD

❙ Central nervous system Definition

The central nervous system (CNS) is composed of the brain and spinal cord. The brain receives sensory information from the nerves that pass through the spinal cord, as well as other nerves such as those from sensory organs involved in sight and smell. Once received, the brain processes the sensory signals and initiates responses. The spinal cord is the principle route for the passage of sensory information to and from the brain. Information flows to the central nervous system from the peripheral nervous system, which senses signals from the environment outside the body (sensory-somatic nervous system) and from the internal environment (autonomic nervous system). The brain’s responses to incoming information flow through the spinal cord nerve network to the various effector organs and tissue regions where the target responsive action will take place.

Description Brain The brain is divided into three major anatomical regions, the prosencephalon (forebrain), mesencephalon

(midbrain), and the rhombencephalon (hindbrain). The brain also contains a ventricular system, which consists of four ventricles (internal cavities): two lateral ventricles, a third ventricle, and a fourth ventricle. The ventricles are filled with cerebrospinal fluid and are continuous with the spinal canal. The ventricles are connected via two interventricular foramen (connecting the two lateral ventricles to the third venticle), and a cerebral aqueduct (connecting the third ventricle to the fourth ventricle). The brain and spinal cord are covered by three layers of meninges (dura matter, arachnoid matter, and pia mater) that dip into the many folds and fissures. The meninges are three sheets or layers of connective tissue that cover all of the spinal cord and the brain. Infections of the meninges are called meningitis. Bacterial, viral, and protozoan meningitis are serious and require prompt medical attention. Between the arachnoid and the pia matter is a fluid called the cerebrospinal fluid. Bacterial infections of the cerebrospinal fluid can occur and are life-threatening. GROSS ANATOMY OF THE BRAIN The prosencephalon is divided into the diencephalon and the telencephalon (also known as the cerebrum). The cerebrum contains the two large bilateral hemispherical cerebral cortex that are responsible for the intellectual functions and house the neural connections that integrate, personality, speech, and the interpretation of sensory data related to vision and hearing.

The midbrain, or mesencephalon region, serves as a connection between higher and lower brain functions, and contains a number of centers associated with regions that create strong drives to certain behaviors. The midbrain is involved in body movement. The so-called pleasure center is located here, which has been implicated in the development of addictive behaviors. The rhombencephalon, consisting of the medulla oblongata, pons, and cerebellum, is an area largely devoted to lower brain functions, including autonomic functions involved in the regulation of breathing and general body coordination. The medulla oblongata is a cone-like knot of tissue that lies between the spinal cord and the pons. A median fissure (deep, convoluted fold) separates swellings (pyramids) on the surface of the medulla. The pons (also known as the metencephalon) is located on the anterior surface of the cerebellum and is continuous with the superior portion of the medulla oblongata. The pons contains large tracts of transverse fibers that serve to connect the left and right cerebral hemispheres. The cerebellum lies superior and posterior to the pons at the back base of the head. The cerebellum consists of left and right hemispheres connected by the vermis. Specialized tracts (peduncles) of neural tissue also connect the

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Resources

Central nervous system

Central and peripheral nervous systems

Autonomic nervous system Parasympathetic nerves Sympathetic nerves

CNS (brain and spinal cord)

PNS (motor and sensory nerves)

(Illustration by Frank Forney.)

Key Terms Central nervous system (CNS) Composed of the brain and spinal cord.

cerebellum with the midbrain, pons, and medulla. The surface of the cerebral hemispheres (the cortex) is highly convoluted into many folds and fissures. The midbrain serves to connect the forebrain region to the hindbrain region. Within the midbrain a narrow aqueduct connects ventricles in the forebrain to the hindbrain. There are four distinguishable surface swellings (colliculi) on the midbrain. The midbrain also contains a highly vascularized mass of neural tissue called the red nucleus that is reddish in color (a result of the vascularization) compared to other brain structures and landmarks. 202

Although not visible from an exterior inspection of the brain, the diencephalon contains a dorsal thalamus (with a large posterior swelling termed the pulvinar) and a ventral hypothalamus that forms a border of the third ventricle of the brain. In this third ventral region lies a number of important structures, including the optic chiasma (the region where the ophthalmic nerves cross) and infundibulum. Obscuring the diencephalon are the two large, welldeveloped, and highly convoluted cerebral hemispheres that comprise the cerebrum. The cerebrum is the largest of the regions of the brain. The corpus callosum is connected to the two large cerebral hemispheres. Within each cerebral hemisphere lies a lateral ventricle. The cerebral hemispheres run under the frontal, parietal, and occipital bones of the skull. The gray matter cortex is highly convoluted into folds (gyri) and the covering meninges dip deeply into the narrow gaps between the folds (sulci). The divisions of the superficial anatomy of the brain use the gyri and sulci

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In a reversal of the pattern found within the spinal cord, the cerebral hemispheres have white matter tracts on the inside of the hemispheres and gray matter on the outside or cortex regions. Masses of gray matter that are present within the interior white matter are called basal ganglia or basal nuclei. Spinal cord The spinal cord is a long column of neural tissue that extends from the base of the brain, downward (inferiorly) through a canal created by the spinal vertebral foramina. The spinal cord is between 16.9 and 17.7 inches (43 and 45 centimeters) long in the average woman and man, respectively. The spinal cord usually terminates at the level of the first lumbar vertebra. The spinal cord is enclosed and protected by the vertebra of the spinal column. There are four regions of vertebrae. Beginning at the skull and moving downward, there are the eight cervical vertebrae, 12 thoracic vertebrae, five lumbar vertebrae, five sacral vertebrae, and one set of fused coccygeal vertebra. Along the length of the spinal cord are positioned 31 pairs of nerves. These are known as mixed spinal nerves, as they convey sensory information to the brain and response information back from the brain. Spinal nerve roots emerge from the spinal cord that lies within the spinal canal. Both dorsal and ventral roots fuse in the intervertebral foramen to create a spinal nerve. Although there are only seven cervical vertebra, there are eight cervical nerves. Cervical nerves one through seven (C1–C7) emerge above (superior to) the corresponding cervical vertebrae. The last cervical nerve (C8) emerges below (inferior to) the last cervical vertebrae from that point downward the spinal nerves exit below the corresponding vertebrae for which they are named. In the spinal cord of humans, the myelin-coated axons are on the surface and the axon-dendrite network is on the inside. In cross-section, the pattern of contrasting color of these regions produces an axon-dendrite shape that is reminiscent of a butterfly. The nerves of the spinal cord correspond to the arrangement of the vertebrae. There are 31 pairs of nerves, grouped as eight cervical pairs, 12 thoracic pairs, five lumbar pairs, five sacral pairs, and one coccygeal pair. The nerves toward the top of the cord are oriented almost horizontally. Those further down are oriented on a progressively upward slanted angle toward the bottom of the cord.

Toward the bottom of the spinal cord, the spinal nerves connect with cells of the sympathetic nervous system. These cells are called pre-ganglionic and ganglionic cells. One branch of these cells is called the gray ramus communicans and the other branch is the white ramus communicans. Together they are referred to as the rami. Other rami connections lead to the pelvic area. The bi-directional (two-way) communication network of the spinal cord allows the reflex response to occur. This type of rapid response occurs when a message from one type of nerve fiber, the sensory fiber, stimulates a muscle response directly, rather than the impulse traveling to the brain for interpretation. For example, if a hot stove burner is touched with a finger, the information travels from the finger to the spinal cord and then a response to move muscles away from the burner is sent rapidly and directly back. This response is initiated when speed is important.

Development and histology of the CNS Both the spinal cord and the brain are made up of structures of nerve cells called neurons. The long main body extension of a neuron is called an axon. Depending on the type of nerve, the axons may be coated with a material called myelin. Both the brain and spinal cord components of the central nervous system contain bundles of cell bodies (out of which axons grow) and branched regions of nerve cells that are called dendrites. Between the axon of one cell body and the dendrite of another nerve cell is an intervening region called the synapse. In the spinal cord of humans, the myelin-coated axons are on the surface and the axon-dendrite network is on the inside. In the brain, this arrangement is reversed. The brain begins as a swelling at the cephalic end of the neural tube that ultimately will become the spinal cord. The neural tube is continuous and contains primitive cerebrospinal fluids. Enlargements of the central cavity (neural tube lumen) in the region of the brain become the two lateral, third, and forth ventricles of the fully developed brain. The embryonic brain is differentiated in several anatomical regions. The most cephalic region is the telencephalon. Ultimately, the telencephlon will develop the bilateral cerebral hemispheres, each containing a lateral ventricle, cortex (surface) layer of gray cells, a white matter layer, and basal nuclei. Caudal (inferior) to the telecephalon is the diencephalon that will develop the epithalamus, thalamus, and hypothalamus Caudal to the diencephalon is the mesencephalon, the midbrain region that includes the cerebellum and pons. Within the myelencephalon region is the medulla oblongata. Neural development inverts the gray matter and white matter relationship within the brain. The outer cortex is

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as anatomical landmarks to define particular lobes of the cerebral hemispheres. As a rule, the lobes are named according to the particular bone of the skull that covers them. Accordingly, there are left and right frontal lobes, parietal lobes, an occipital lobe, and temporal lobes.

Central nervous system stimulants

composed of gray matter, while the white matter (myelinated axons) lies on the interior of the developing brain. The meninges that protect and help nourish neural tissue are formed from embryonic mesoderm that surrounds the axis established by the primitive neural tube and notochord. The cells develop many fine capillaries that supply the highly oxygen-demanding neural tissue.

Diseases and disorders of the CNS Diseases that affect the nerves of the central nervous system include rabies, polio, and sub-acute sclerosing panencephalitis. Such diseases affect movement and can lead to mental incapacitation. The brain is also susceptible to disease, including toxoplasmosis and the development of empty region due to prions. Such diseases cause a wasting away of body function and mental ability. Brain damage can be so compromised as to be lethal. Resources BOOKS

Bear, M., et al. Neuroscience: Exploring the Brain. Baltimore: Williams & Wilkins, 1996. Goetz, C. G., et al. Textbook of Clinical Neurology. Philadelphia: W.B. Saunders Company, 1999. Goldman, Cecil. Textbook of Medicine, 21st ed. New York: W.B. Saunders Co., 2000. Guyton & Hall. Textbook of Medical Physiology, 10th ed. New York: W.B. Saunders Company, 2000. Tortora, G. J., and S. R. Grabowski. Principles of Anatomy and Physiology, 9th ed. New York: John Wiley and Sons Inc., 2000.

Brian Douglas Hoyle, PhD Paul Arthur

❙ Central nervous system stimulants

Definition Central nervous system (CNS) stimulants are drugs that increase activity in certain areas of the brain. These drugs are used to improve wakefulness in patients that have narcolepsy. CNS stimulants are also used to treat patients that have attention deficit hyperactivity disorder (ADHD). There are four different types of central nervous system stimulants available in the United States: mixed amphetamine salts (brand name Adderall); dextroamphetamine (Dexedrine and Dextrostat); methylphenidate (Ritalin, Metadate, Methylin, and Concerta); and pemoline (Cylert). 204

Purpose Central nervous system stimulants are used to keep patients who suffer from narcolepsy from falling asleep. Narcolepsy is a disorder that causes people to fall asleep during daytime hours. These drugs are also used to treat behavioral symptoms associated with attention deficit hyperactivity disorder. Although it seems contradictory to give patients with ADHD drugs that are stimulants, these medications are often effective at treating symptoms of impulsivity, inattention, and hyperactivity, which are hallmark features of the disorder.

Description The exact way that CNS stimulants work in treating narcolepsy and ADHD is not understood. The drugs’ mechanism of action appears to involve enhanced activity of two neurotransmitters in the brain, norepinephrine and dopamine. Neurotransmitters are naturally occurring chemicals that regulate transmission of nerve impulses from one cell to another. A proper balance between the various neurotransmitters in the brain is necessary for healthy mental well-being. Central nervous system stimulants increase the activities of norepinephrine and dopamine in two different ways. First, the CNS stimulants increase the release of norepinephrine and dopamine from brain cells. Second, the CNS stimulants may also inhibit the mechanisms that normally terminate the actions of these neurotransmitters. As a result of the dual activities of central nervous system stimulants, norepinephrine and dopamine have enhanced effects in various regions of the brain. Some of these brain areas are involved with controlling wakefulness and others are involved with controlling motor activities. It is believed that CNS stimulants restore a proper balance of neurotransmitters, which alleviates symptoms and features associated with narcolepsy and ADHD. Although the intended actions of central nervous system stimulants are in the brain, their actions may also affect norepinephrine in other parts of the body. This can cause unwanted side effects such as increased blood pressure and heart arrhythmias due to reactions of norepinephrine on the cardiovascular system.

Recommended dosage The usual dosage of amphetamine salts is 5–60 mg per day taken two or three times a day, with at least 4–6 hours between doses. The extended release form of amphetamine salts is taken as 10–30 mg once a day. Like amphetamine salts, the dose of immediate-release methylphenidate tablets is also 5–60 mg per day taken two or three times a day. Additionally, methylphenidate is

GALE ENCYCLOPEDIA OF NEUROLOGICAL DISORDERS

Attention deficit hyperactivity disorder (ADHD) A mental disorder characterized by impulsiveness, lack of attention, and hyperactivity. Milligram One thousandth of a gram; the metric measure equals 0.035 ounces. Narcolepsy An extreme tendency to fall asleep when surroundings are quiet or monotonous. Neurotransmitter Naturally occurring chemicals that regulate transmission of nerve impulses from one cell to another.

Central nervous system stimulants may increase heart rates and cause irregular heart rhythms, especially at high doses. Symptoms of excessive stimulation of the central nervous system include restlessness, difficulty sleeping, tremor, headaches, and even psychotic episodes. Loss of appetite and weight loss may also occur with central nervous system stimulants. It is necessary to monitor liver function regularly in patients who take pemoline since this drug has been associated with life-threatening liver disease.

Interactions available in sustained-release dosage forms and extended-release dosage forms, which are typically taken only once a day. The usual dosage of dextroamphetamine is 5–60 mg per day given two or three times a day, with at least 4–6 hours between doses. A sustained-release form of dextroamphetamine is also available, which may be given once a day. The recommended dose of pemoline is 37.5–112.5 mg per day taken only once a day. However, due to pemoline’s association with life-threatening liver dysfunction, pemoline is rarely used at the present time. The therapeutic effects of central nervous system stimulants are usually apparent within the first 24 hours of taking the drugs. If effects are not evident, the dosages of CNS stimulants may be slowly increased at weekly intervals. CNS stimulants should always be used at the lowest effective dosages to minimize unwanted side effects. When the drugs are used for treating ADHD in children, therapy should be interrupted occasionally to determine whether symptoms reoccur and whether the drug is still necessary.

CNS stimulants should not be administered with certain types of antidepressant medications, including monoamine oxidase inhibitors (MAOIs) and selective serotonin reuptake inhibitors (SSRIs). Patients taking CNS stimulants should avoid MAOIs since the combination may elevate blood pressure to dangerously high levels, while SSRIs are best avoided since they may increase the central nervous system effects of CNS stimulants if the drugs are taken together. Antacids may prevent CNS stimulants from being eliminated by the body and can increase the side effects associated with use of the stimulants. Resources BOOKS

Dipiro, J. T., R. L. Talbert, G. C. Yee, et al., eds. Pharmacotherapy: A Pathophysiologic Approach, 4th edition. Stamford, CT: Appleton and Lange, 1999. Facts and Comparisons Staff. Drug Facts and Comparisons, 6th edition. St. Louis, MO: A Wolter Kluwer Company, 2002.

Kelly Karpa, PhD, RPh

Precautions Central nervous system stimulants are widely abused street drugs. Abuse of these drugs may cause extreme psychological dependence. As a result, new hand-written prescriptions must be obtained from physicians each month and any time a dosage adjustment is made. These drugs are best avoided in patients with a prior history of drug abuse. CNS stimulants may cause anorexia and weight loss. Additionally, these drugs slow growth rates in children. Height and weight should be checked every three months in children who need to use these medications on a longterm basis. The use of CNS stimulants should be avoided in patients with even mild cases of high blood pressure since the drugs may elevate blood pressure further.

❙ Central pain syndrome Definition

Central pain syndrome is a type of pain that occurs because of injuries to the brain or spinal cord.

Description Central pain syndrome can occur in conjunction with a number of conditions involving the brain or spinal cord, including stroke; traumatic injury to, or tumors involving, the brain or spinal cord; Parkinson’s disease; multiple sclerosis; or epilepsy.

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Key Terms

Side effects

Central pain syndrome

The pain of central pain syndrome is an extremely persistent, intractable type of pain that can be quite debilitating and depressing to the sufferer. The pain may be localized to a particular part of the body (such as the hands or feet), or may be more widely distributed. The quality of the pain may remain the same or may change. Some of the types of pain experienced in central pain syndrome include sensations of crampy muscle spasms; burning; an increased sensitivity to painful stimuli; pain brought on by normally unpainful stimuli (such as light touch or temperature changes); shooting, lightening, or electric shock–like pains; tingling, pins-and-needles, stinging, numbness, or burning pain; sense of painful abdominal or bladder bloating and burning sensations in the bladder. Central pain syndrome can be divided into two categories: pain related to prior spinal cord injury and pain related to prior brain injury. Spinal cord–related pain occurs primarily after traumatic injury, usually due to motor vehicle accidents. Other reasons for spinal cord–related pain include complications of surgery, tumors, congenital disorders (conditions present at birth), blood vessel– related injury (such as after a spinal cord infarction or stroke), and inflammatory conditions involving the spinal cord. Brain-related central pain usually follows a stroke, although tumors and infection may also lead to brainrelated central pain.

Demographics Eight percent of all stroke patients will experience central pain syndrome; 5% will experience moderate to severe pain. The risk of developing central pain syndrome is higher in older stroke patients, striking about 11% of patients over the age of 80. Spinal cord–related pain occurs in a very high percentage; research suggests a range of 2585% of all individuals with spinal cord injuries will experience central pain syndrome.

Diagnosis Diagnosis is usually based on the knowledge of a prior spinal cord or brain injury, coupled with the development of a chronic pain syndrome. Efforts to delineate the cause of the pain may lead to neuroimaging (CT and MRI scanning) of the brain, spinal cord, or the painful anatomical area (abdomen, limbs); electromyographic and nerve conduction studies may also be performed. In many cases of central pain syndrome, no clear-cut area of pathology will be uncovered, despite diagnostic testing. In fact, this is one of the frustrating and confounding characteristics of central pain syndrome; the inability to actually delineate an anatomical location responsible for generating the pain, which creates difficulty in addressing the pain.

Treatment team Neurologists will usually be the mainstay for treating central pain syndrome. Physical and occupational therapists may help an individual facing central pain syndrome obtain maximal relief and regain optimal functioning. Psychiatrists or psychologists may be helpful for supportive psychotherapy, particularly in patients who develop depression related to their chronic pain.

Treatment

Causes and symptoms In general, central pain syndrome is thought to occur either because the transmission of pain signals in the nerve tracts of the spinal cord is faulty, or because the brain isn’t processing pain signals properly. Although details regarding the origin of central pain syndrome remain cloudy, some of the mechanisms that may contribute to its development include muscle spasm; spasticity of muscles (chronically increased muscle tone); instability of the vertebral column (due to vertebral fracture or damage to ligaments); compression of nerve roots; the development of a fluid-filled area of the spinal cord (called a syringomyelia), which puts pressure on exiting nerves; and overuse syndrome (muscles that are used to compensate for those that no longer function normally are overworked, resulting in muscle strain). 206

The pain of central pain syndrome can begin within days of the causative insult, or it can be delayed for years (particularly in stroke patients). While the specific symptoms of central pain syndrome may vary over time, the presence of some set of symptoms is essentially continuous once they begin. The pain is usually moderate to severe in nature and can be very debilitating. Symptoms may be made worse by a number of conditions, such as temperature change (especially exposure to cold), touching the painful area, movement, and emotions or stress. The pain is often difficult to describe.

A variety of medications may be used to treat central pain syndrome. Injection of IV lidocaine can significantly improve some aspects of central pain syndrome, but the need for intravenous access makes its chronic use relatively impractical. Tricyclic antidepressants (such as nortriptyline or amitriptyline) and antiepileptic drugs (such as lamotrigine, carbamazepine, gabapentin, topiramate) have often been used for neurogenic pain syndromes (pain due to abnormalities in the nervous system), and may be helpful to sufferers of central pain syndrome. When muscle spasms or spasticity are part of the central pain syndrome, a variety of medications may be helpful, including baclofen, tizanidine, benzodiazepines, and dantrolene sodium. In some cases, instilling medications (such as baclofen) directly into the cerebrospinal fluid around the

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Severe, intractable pain may be treated by severing causative nerves or even severing certain nervous connections within the spinal cord. However, while this seems to provide pain relief in the short run, over time, about 6080% of patients develop the pain again. Counterstimulation uses electrodes implanted via needles in the spinal cord or specific nerves. These electrodes stimulate the area with electric pulses in an effort to cause a phenomenon referred to as “counter-irritation,” which seems to interrupt the transmission of painful impulses. Deep brain stimulation requires the surgical implanatation of an electrode deep in the brain. A pulse generator that sends electricity to the electrode is implanted in the patient’s chest, and a magnet passed over the pulse generator by the patient activates the brain electrode, stimulating the thalamic area.

Prognosis Although central pain syndrome is never fatal, it can have serious consequences for an individual’s level of functioning. Severe, chronic pain can be very disabling and have serious psychological consequences. Furthermore, central pain syndrome remains difficult to completely resolve; treatments may provide relief, but rarely provide complete cessation of pain. Resources BOOKS

Braunwald, Eugene, et al., eds. Harrison’s Principles of Internal Medicine. NY: McGraw-Hill Professional, 2001. Frontera, Walter R., ed. Essentials of Physical Medicine and Rehabilitation, 1st ed. Philadelphia: Hanley and Belfus, 2002. Goldman, Lee, et al., eds. Cecil Textbook of Internal Medicine. Philadelphia: W. B. Saunders Company, 2000. PERIODICALS

Nicholson, Bruce D. “Evaluation and treatment of central pain syndromes.” Neurology 62, no. 5 (March 2004): 30–36. WEBSITES

National Institute of Neurological Disorders and Stroke (NINDS). Central Pain Syndrome Fact Sheet. . ORGANIZATIONS

American Chronic Pain Association (ACPA). P.O. Box 850, Rocklin , CA 95677-0850. 916-632-0922 or 800-5333231; Fax: 916-632-3208. [email protected]. .

American Pain Foundation. 201 North Charles Street Suite 710, Baltimore , MD 21201-4111. 410-783-7292 or 888615-PAIN (7246); Fax: 410-385-1832. info@pain foundation.org. . National Foundation for the Treatment of Pain. P.O. Box 70045, Houston , TX 77270. 713-862-9332 or 800-5333231; Fax: 713-862-9346. [email protected]. .

Rosalyn Carson-DeWitt, MD

Cerebellar dysfunction see Ataxia Cerebellar-pontine angle tumors see Vestibular Schwanomma

❙ Cerebellum Definition

The cerebellum is a cauliflower-shaped brain structure located just above the brainstem, beneath the occipital lobes at the base of the skull.

Description The word cerebellum comes from the Latin word for “little brain.” The cerebellum has traditionally been recognized as the unit of motor control that regulates muscle tone and coordination of movement. There is an increasing number of reports that support the idea that the cerebellum also contributes to non-motor functions such as cognition (thought processes) and affective state (emotion). The cerebellum comprises approximately 10% of the brain’s volume and contains at least half of the brain’s neurons. The cerebellum is made up of two hemispheres (halves) covered by a thin layer of gray matter known as the cortex. Beneath the cortex is a central core of white matter. Embedded in the white matter are several areas of gray matter known as the deep cerebellar nuclei (the fastigial nucleus, the globise-emboliform nucleus, and the dentate nucleus). The cerebellum is connected to the brainstem via three bundles of fibers called peduncles (the superior, middle, and inferior).

Anatomy The cerebellum is a complex structure. At the basic level, it is divided into three distinct regions: the vermis, the paravermis (also called the intermediate zone), and the cerebellar hemispheres. Fissures, deep folds in the cortex that extend across the cerebellum, further subdivide these regions into 10 lobules, designated lobules I–X. Two of

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spinal cord may improve spasms and spasticity. Newer therapy with injections of botulinum toxin may help relax painfully spastic muscles. Chronically spastic, painful muscles may also be treated surgically, by cutting through tendons (tendonotomy).

Cerebellum

Key Terms Autoantibodies Antibodies that attack the body’s own cells or tissues. Axon A long, threadlike projection that is part of a neuron (nerve cell). Gray matter Areas of the brain and spinal cord that are comprised mostly of unmyelinated nerves. Multiple sclerosis A progressive, autoimmune disease of the central nervous system characterized by damage to the myelin sheath that covers nerves. The disease, which causes progressive paralysis, is marked by periods of exacerbation and remission. White matter A substance, composed primarily of myelin fibers, found in the brain and nervous system that protects nerves and allows messages to be sent to and from the brain and various parts of the body. Also called white substance.

these fissures in particular, the posterolateral fissure and the primary fissure, separate the cerebellum into three lobes that have different functions: the flocculonodular lobe, or the vestibulocerebellum (lobule X); the anterior lobe (lobules I–V); and the posterior lobe (lobules VI–IX). The cerebellum plays an important role in sending and receiving messages (nerve signals) necessary for the production of muscle movements and coordination. There are both afferent (input) and efferent (output) pathways. The major input pathways (also called tracts) include: • dorsal spinocerebellar pathway • ventral spinocerebellar pathway

Function The flocculonodular lobe helps to maintain equilibrium (balance) and to control eye movements. The anterior lobe parts of the posterior lobe (the vermis and paravermis) form the spinocerebellum, a region that plays a role in control of proximal muscles, posture, and locomotion such as walking. The cerebellar hemispheres (part of the posterior lobe) are collectively known as the cerebrocerebellum (or the pontocerebellum); they receive signals from the cerebral cortex and aid in initiation, coordination, and timing of movements. The cerebrocerebellum is also thought to play a role in cognition and affective state. The cerebellum has been reported to play a role in psychiatric conditions such as schizophrenia, autism, mood disorders, dementia, and attention deficit hyperactivity disorder (ADHD). Currently, the relationship between the cerebellum and psychiatric illness remains unclear. It is hoped that further research will reveal insights into the cerebellar contribution to these conditions.

Disorders There are a variety of disorders that involve or affect the cerebellum. The cerebellum can be damaged by factors including: • toxic insults such as alcohol abuse • paraneoplastic disorders; conditions in which autoantibodies produced by tumors in other parts of the body attack neurons in the cerebellum • structural lesions such as strokes, multiple sclerosis, or tumors

• corticopontocerebellar pathway • cerebo-olivocerebellar pathway

• inherited cerebellar degeneration such as in Friedreich ataxia or one of the spinocerebellar ataxias

• cerebroreticulocerebellar pathway • cuneocerebellar pathway • vestibulocerebellar pathway The major output pathways include the following: • globose-emboliform-rubral pathway • fastigial reticular pathway • dentatothalamic pathway • fastigial vestibular pathway There is a network of fibers (cells) within the cerebellum that monitors information to and from the brain and the spinal cord. This network of neural circuits links the input pathways to the output pathways. The Purkinje 208

fibers and the deep nuclei play key roles in this communication process. The Purkinje fibers regulate the deep nuclei, which have axons that send messages out to other parts of the central nervous system.

• congenital anomalies such as cerebellar hypoplasia (underdevelopment or incomplete development of the cerebellum) found in Dandy-Walker syndrome, or displacement of parts of the cerebellum such as in Arnold-Chiari malformation Typical symptoms of cerebellar disorders include hypotonia (poor muscle tone), movement decomposition (muscular movement that is fragmented rather than smooth), dysmetria (impaired ability to control the distance, power, and speed of an act), gait disturbances (abnormal pattern of walking), abnormal eye movement, and dysarthria (problems with speaking).

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Dawn Cardeiro, MS

BOOKS

Manto, Mario U., and Massimo Pandolfo, eds. The Cerebellum and its Disorders. Cambridge, England: Cambridge University Press, 2001. De Zeeuw, C. I., P. Strata, and J. Voogd, eds. The Cerebellum: From Structure to Control. St Louis, MO: Elsevier Science, 1997. PERIODICALS

Daum, I., B. E. Snitz, and H. Ackermann. “Neuropsychological Deficits in Cerebellar Syndromes.” International Review of Psychiatry 13 (2001): 268–275. Desmond, J. E. “Cerebellar Involvement in Cognitive Function: Evidence from Neuroimaging.” International Review of Psychiatry 13 (2001): 283–294. Leroi, I., E. O’Hearn, and R. Margolis. “Psychiatric Syndromes in Cerebellar Degeneration.” International Review of Psychiatry 13 (2001): 323–329. O’Hearn, E., and M. E. Molliver. “Organizational Principles and Microcircuitry of the Cerebellum.” International Review of Psychiatry 13 (2001): 232–246. Rapoport, M. “The Cerebellum in Psychiatric Disorders.” International Review of Psychiatry 13 (2001): 295–301. Schmahmann, J. D. “The Cerebrocerebellar System: Anatomic Substrates of the Cerebellar Contribution to Cognition and Emotion.” International Review of Psychiatry 13 (2001): 247–260. Shill, H. A., and M. Hallett. “Cerebellar Diseases.” International Review of Psychiatry 13 (2001): 261–267. WEBSITES

“BrainInfo Web Site.” Cerebellum Information Page. Neuroscience Division, Regional Primate Research Center, University of Washington, 2000. (May 22, 2004.) . The Cerebellum Database Site. (May 22, 2004). . The National Institute of Neurological Disorders and Stroke (NINDS). Cerebellar Degeneration Information Page. PO Box 5801 Bethesda, MD, 2003. (May 22, 2004). . The National Institute of Neurological Disorders and Stroke (NINDS). Cerebellar Hypoplasia Information Page. PO Box 5801 Bethesda, MD, 2003. (May 22, 2004). . ORGANIZATIONS

National Institute of Mental Health. 6001 Executive Boulevard, Room 8184, MSC 9663, Bethesda, MD 20892-9663. (301) 443-4513 or (866) 615-6464; TTY: (301) 443-8431; Fax: (301) 443-4279. [email protected]. . National Institute of Neurological Disorders and Stroke (NINDS), NIH Neurological Institute. P.O. Box 5801, Bethesda, MD 20824. (301) 496-5751 or (800) 352-9424; TTY: (301) 468-5981. .

Cerebral aneurysm see Aneurysm Cerebral arteriosclerosis see Stroke Cerebral gigantism see Hypoxia, Sotos syndrome

❙ Cerebral angiitis Definition

Cerebral angiitis is an inflammation of the small arteries in the brain.

Description Cerebral angiitis is a type of vasculitis in which an aberrant immune response results in inflammation and destruction of the small arteries that feed brain tissue. As a result of the inflammation, blood clots form within the arteries, compromising blood flow and resulting in decreased oxygen delivery to vulnerable brain tissue. Two types of cerebral angiitis have been recognized. The first type is considered to be an encephalopathic type, which results in wide-spread, slowly progressive damage to the brain. The second type causes abrupt, acute damage to a focal area of the brain, similar to a stroke.

Demographics While cerebral angiitis can affect people of all ages, it is most common in the middle aged. Cerebral angiitis affects slightly more males than females. It may also be responsible for the unusual presentation of vasculitis in children, often following a simple chicken pox infection. Cerebral angiitis can also occur as a rare complication of allogeneic bone marrow transplant (bone marrow transplant received from a donor).

Causes and symptoms Cerebral angiitis may occur spontaneously, with no known cause, or in conjunction with, or as a sequela to (an aftereffect of) a variety of viral infections, including herpes zoster (shingle), varicella zoster (chicken pox), and HIV/AIDS. Symptoms can include slowly progressive headache, nausea, vomiting, stiff neck, confusion, irritability, loss of memory, seizures, and dementia. Cerebral angiitis may also cause the sudden onset of more acute and focal loss

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Resources

Cerebral cavernous malformation

Prognosis

Key Terms Encephalopathic Widespread brain disease or dysfunction. Vasculitis A condition characterized by inflammation of blood vessels.

Untreated cerebral angiitis will inevitably progress to death, often within a year of the onset of the disease. More research is needed to define the prognosis of treated cerebral angiitis; current research suggests that slightly more than half of all treated patients have a good outcome. Resources BOOKS

of function, such as sudden loss of the use of one side of the body or the inability to speak.

Sergent, John S. “Polyarteritis and related disorders.” In Kelley’s Textbook of Rheumatology, 6th edition, edited by Shaun Ruddy, et al. St. Louis: W. B. Saunders Company, 2001. PERIODICALS

Diagnosis Cerebral angiitis may be diagnosed by examining a sample of cerebrospinal fluid, which will likely reveal increased levels of protein and abnormal white cell activity. MRI scanning of the brain will usually show a diffuse pattern of lesions throughout the white matter of the brain, although the stroke-like type of cerebral angiitis may reveal a more focal area of damage. Biopsy of a sample of brain tissue is the most definitive diagnostic test; it will reveal inflammation and immune system activity affecting the damaged small arteries of the brain.

Rollnik, J. D., A. Brandis, K. Dehghani, J. Bufler, M. Lorenz, F. Heidenreich, and F. Donnerstag. “Primary angiitis of CNS (PACNS).” Nervenarzt 72, no. 10 (October 2001): 798–801. Singh, S., S. John, T. P. Joseph, and T. Soloman. “Primary angiitis of the central nervous system: MRI features and clinical presentation.” Australasian Radiology 47, no. 2 (June 2003): 127–134. Singh, S., S. John, T. P. Joseph, and T. Soloman. “Prognosis of patients with suspected primary CNS angiitis and negative brain biopsy.” Neurology 61, no. 6 (September 2003) 831–833.

Treatment team

Rosalyn Carson-DeWitt, MD

Individuals with cerebral angiitis may be treated by a neurologist or a rheumatologist.

Treatment Treatment for cerebral angiitis addresses the inflammation and the immune response, both of which are responsible for the complications of the condition. Corticosteroids (to quell inflammation) and cyclophosphamide (to dampen the immune system) may be given in tandem, often at high doses for about six weeks, and then at lower doses for up to a year. Occasionally, symptoms rebound after the dose is dropped, requiring that the higher dose be reutilized; even after supposed cure, relapse may supervene, necessitating another course of corticosteroids and cyclophosphamide. Some patients with cerebral angiitis will also benefit from the administration of anticoagulant agents to thin the blood and prevent arterial obstruction by blood clots.

Recovery and rehabilitation The type of rehabilitation program required will depend on the types of deficits caused by cerebral angiitis, but may include physical therapy, occupational therapy, and speech and language therapy. 210

❙ Cerebral cavernous malformation

Definition Cerebral cavernous malformations (CCM) are tangles of malformed blood vessels located in the brain and/or spinal cord.

Description The blood vessels composing a cerebral cavernous malformation are weak and lack supporting tissue, thus they are prone to bleed. If seen under a microscope, a cavernous malformation appears to be composed of fairly large blood-filled caverns. A characteristic feature of a CCM is slow bleeding, or oozing, as opposed to the dangerous sudden rupture of an aneurysm (a weak, bulging area of a blood vessel). However, depending on the size and location of the CCM, and the frequency of bleeding, a CCM can also create a dangerous health emergency. Cerebral cavernous malformations are also known as cavernomas or cavernous angiomas.

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Aneurysm A weak, bulging area of a blood vessel. Autosomal dominant inheritance A pattern of inheritance where only one parent must have the illness for it to be passed on to offspring. The risk of an affected parent passing the condition to an offspring is 50% with each pregnancy.

CCM is usually distinct from the surrounding brain tissue and resembles a mass or a blood clot. It can occur either sporadically or in a familial (inherited) pattern. Usually, only one or two lesions are present when the CCM occurs sporadically. Those with a familial pattern of CCM usually have multiple lesions of malformed blood vessels, along with a strong family history of stroke or related neurological difficulties. Familial CCM has a pattern of autosomal dominant inheritance, meaning that only one parent must have the illness for it to be passed on to offspring, and the risk of an affected parent passing the condition to an offspring is 50%. The first gene (CCM1) involved in this disease was recently identified and mapped to the long arm of chromosome 7. Additionally, two other genes responsible for CCM formation were also identified, one mapped to the short arm of chromosome 7 (the CCM2 gene) and the other mapped to the long arm of chromosome 3 (the CCM3 gene). The size of the malformation varies greatly and can change depending on the amount and severity of each bleeding episode. Typically, they range from something microscopic to something the size of an orange. It is possible for a CCM not to bleed, and the ones that do so, may not necessarily bleed with the severity or intensity that requires surgery. Depending on the size and location of the lesion, the blood can reabsorb causing symptoms to disappear.

Demographics Cavernous malformations occur in people of all races and both sexes. The male-female ratio is about equal. Family history may be predictive, especially in patients of Hispanic descent. CCM can be found in any region of the brain, can be of varying size, and present with varying symptoms. In a general population of one million people, 0.5% or 5,000 people may be found to have a cavernous malformation, although many are not symptomatic. In the United States alone, 1.5 million people, or 1 in 200, are estimated to have some form of CCM. This translates to approximately 0.5% of the population. Approximately 20–30% of the diagnoses are made in children and

Causes and symptoms Most familial cerebral cavernous malformations are present at birth (congenital). They are thought to arise between three and eight weeks of gestation, although the exact mechanism of CCM formation is not understood. Vascular malformations can potentially occur many years after radiation therapy to the brain. Additionally, it is also assumed that severe or repeated head trauma can cause cerebral capillaries to bleed. Over time, the brain attempts to repair itself and control the bleeding by developing a lesion. Researchers assume that these theories may answer the question why some people develop the sporadic form of CCM. Although these common neurovascular lesions affect almost 0.5% of the population, only 20–30% of these individuals experience symptoms. Symptoms include seizures, dizziness, stroke, vomiting, uncontrollable hiccups, periodic weakness, irritability and/or changes in personality, headaches, difficulty speaking, vision problems or, rarely, brain hemorrhage. Symptoms are caused by the pressure of accumulated blood in and around the CCM on adjacent brain tissue. If the area of bleeding is small, it may take several subsequent bleeding episodes until enough pressure is built up in order for symptoms to be noticeable. The CCM could also bleed substantially, causing immediate problems and symptoms. Finally, the CCM could remain dormant without any evidence of bleeding.

Diagnosis Cerebral cavernous malformations are usually diagnosed by computerized axial tomography (CAT) scan or, more accurately, a magnetic resonance imaging (MRI) scan with gradient echo sequencing. MRI has provided the ability to image and localize otherwise hidden lesions of the brain and provide accuracy of diagnosis before surgery. Both the MRI and CAT scans produce images of slices through the brain. These tests help physicians to see exactly where the cavernoma is located. Cavernomas cannot be seen on a cerebral angiogram. Often, CCMs are diagnosed when the person becomes symptomatic. However, it is common for CCMs to be diagnosed by accident when a CAT scan or MRI is conducted to investigate other health problems. Despite the presence of a CCM, it often remains inactive, meaning there is no evidence that the lesion produces bleeding.

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Key Terms

60% of affected adults are diagnosed in their 20s and 30s. It is estimated that approximately 20 million people worldwide have some kind of vascular malformation.

Cerebral cavernous malformation

Treatment team Treatment for CCMs must be specific for each case. A team of cerebrovascular experts (neurologists, neurosurgeons, neuroradiologists, and radiation oncologists), together with the patient and families, decide on whether treatment is necessary and the best treatment option.

lesions. Persons treated surgically experience remission or a reduction of symptoms in most cases. Approximately half of patients experience elimination of seizures, and the remainder usually have fewer, less frequent seizures. Successfully excised CCM lesions are considered cured, and it is unusual for them to return.

Special concerns

Treatment There are three main treatment options for CCM, including observation, stereotactic radiosurgery, and surgery. If the person with CCM has no symptoms, the first treatment option is to simply observe the CCM with periodic MRI scans to assess for change. This option may be indicated if the lesion is discovered incidentally. Stereotactic radiosurgery involves delivering highlyfocused radiation in a single treatment to the CCM. This has been used almost exclusively for lesions causing repeated hemorrhages located in areas of the brain that are not surgically accessible. It is often difficult to determine if radiosurgery is effective unless the lesion never bleeds again. In certain cases, radiosurgery has likely decreased the repeat hemorrhage rate; however, radiosurgery has never been shown to completely eliminate the malformation. Surgery is the most common option when treatment is necessary. Because these malformations are so distinct from the surrounding brain tissue, cavernous malformations often can be completely removed without producing any new problems. It is very important to remove the entire malformation as it can regenerate if a small piece is left behind. The risk of the operation depends on the size and location of the cavernous malformation and the general health of the patient.

Clinical trials Although there are no clinical trials for treatment of CCM ongoing as of early 2004, much of the current research focuses on the genetics of the disorder. Duke University’s Center for Inherited Neurovascular Diseases was recruiting individuals with familial CCM for participation in research designed to develop a blood test for detecting CCM. For information about participating in the study, contact Ms. Sharmila Basu at (410) 614–0729, or via email at [email protected].

There are differing opinions about activity restriction for a person diagnosed with CCM lesions. Some physicians encourage their patients to continue their usual activities; others advocate avoiding activities where the risk for head trauma is high, such as sports including football, soccer, hockey, skiing, or skating. It is important to discuss this issue with the physician, wear approriate protective equipment when particiapting in sports, and make decisions pertaining to activity level based on the current status of the CCM and general health. It is also helpful to keep an activity record, to document any relationship between activities and symptoms. Resources BOOKS

Klein, Bonnie Sherr, and Persimmon Blackbridge. Out of the Blue: One Woman’s Story of Stroke, Love, and Survival. Berkeley, CA: Wildcat Press, 2000. PERIODICALS

Labauge, P. et al. “Prospective follow-up of 33 asymptomatic patients with familial cerebral cavernous malformations.” Neurology 57 (November 2001): 1825–1828. Laurans, M. S., et al. “Mutational analysis of 206 families with cavernous malformations.” Journal of Neurosurgery 99 (July 2003): 38–43. Narayan, P., and D. L. Barrow. “Intramedullary spinal cavernous malformation following spinal irradiation.” Journal of Neurosurgery 98 (January 2003): 68–72. Reich, P. et al. “Molecular genetic investigations in the CCM1 gene in sporadic cerebral cavernomas.” Neurology 60 (April 2003): 1135–1138. OTHER

“NINDS Cavernous Malformation Information Page.” National Institute of Neurological Disorders and Stroke. (March 1, 2004). . “What Is Cavernous Angioma?” Angioma Alliance. (March 1, 2004). . ORGANIZATIONS

Prognosis Persons experiencing CCM-related symptoms are likely to remain symptomatic or experience a worsening of symptoms without treatment. Frequent or uncontrolled seizures, increase in lesion size on MRI, or hemorrhage are indications for removal of surgically accessible CCM 212

Brain Power Project. P.O. Box 2250, Agoura Hills Englewood, CA 91376. (818) 735-7335; Fax: (818) 706-8246. [email protected]. . National Organization for Rare Disorders (NORD). P.O. Box 1968 (55 Kenosia Avenue), Danbury, CT 06813-1968. (203) 744-0100 or (800) 999-NORD (6673); Fax: (203)

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Beatriz Alves Vianna Iuri Drumond Louro, M.D., Ph.D.

❙ Cerebral circulation Definition

Cerebral circulation, the supply of blood to the brain Understanding how the brain is supplied with blood is important because a significant number of neurological disorders that result in hospital admissions are due to problems with cerebral vascular disease. In some hospitals, nearly half the admissions due to neurologic disorders relate in some form to problems with cerebral circulation. Insufficient supply of blood to the brain can cause fainting (syncope) or a more severe loss of consciousness. A continuous supply of highly oxygenated blood is critical to brain tissue function and a decrease in pressure or oxygenation (percentage of oxygen content) can cause tissue damage within minutes. Depending on a number of other physiological factors (e.g., temperature, etc.), brain damage or death may occur within two to 10 minutes of severe oxygen deprivation. Although there can be exceptions—especially when the body is exposed to cold temperatures—in general, after two minutes of oxygen deprivation, the rate of brain damage increases quickly with time.

Anatomy of cerebral circulation Arterial supply of oxygenated blood Four major arteries and their branches supply the brain with blood. The four arteries are composed of two internal carotid arteries (left and right) and two vertebral arteries that ultimately join on the underside (inferior surface) of the brain to form the arterial circle of Willis, or the circulus arteriosus. The vertebral arteries actually join to form a basilar artery. It is this basilar artery that joins with the two internal carotid arteries and their branches to form the circle of Willis. Each vertebral artery arises from the first part of the subclavian artery and initially passes into the skull via holes (foramina) in the upper cervical vertebrae and the foramen magnum. Branches of the vertebral artery include the anterior and posterior spinal arteries, the meningeal branches, the posterior inferior cerebellar artery, and the medullary arteries that supply the medulla oblongata.

Key Terms Cerebral collateral blood flow Anatomical and physiological mechanisms that allow blood destined for one hemisphere of the brain to crossover and nourish tissue on the other side of the brain when the supply to the other side of the brain is impaired. Circle of Willis Also known as the circulus arteriosus; formed by branches of the internal carotid arteries and the vertebral arteries.

The basilar artery branches into the anterior inferior cerebellar artery, the superior cerebellar artery, the posterior cerebral artery, the potine arteries (that enter the pons), and the labyrinthine artery that supplies the internal ear. The internal carotids arise from the common carotid arteries and pass into the skull via the carotid canal in the temporal bone. The internal carotid artery divides into the middle and anterior cerebral arteries. Ultimate branches of the internal carotid arteries include the ophthalmic artery that supplies the optic nerve and other structures associated with the eye and ethmoid and frontal sinuses. The internal carotid artery gives rise to a posterior communicating artery just before its final splitting or bifurcation. The posterior communicating artery joins the posterior cerebral artery to form part of the circle of Willis. Just before it divides (bifurcates), the internal carotid artery also gives rise to the choroidal artery (also supplies the eye, optic nerve, and surrounding structures). The internal carotid artery bifurcates into a smaller anterior cerebral artery and a larger middle cerebral artery. The anterior cerebral artery joins the other anterior cerebral artery from the opposite side to form the anterior communicating artery. The cortical branches supply blood to the cerebral cortex. Cortical branches of the middle cerebral artery and the posterior cervical artery supply blood to their respective hemispheres of the brain. The circle of Willis is composed of the right and left internal carotid arteries joined by the anterior communicating artery. The basilar artery (formed by the fusion of the vertebral arteries) divides into left and right posterior cerebral arteries that are connected (anastomsed) to the corresponding left or right internal carotid artery via the respective left or right posterior communicating artery. A number of arteries that supply the brain originates at the circle of Willis, including the anterior cerebral arteries that originate from the anterior communicating artery.

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798-2291. [email protected]. .

Cerebral circulation

In the embryo, the components of the circle of Willis develop from the embryonic dorsal aortae and the embryonic intersegmental arteries. The circle of Willis provides multiple paths for oxygenated blood to supply the brain if any of the principal suppliers of oxygenated blood (i.e., the vertebral and internal carotid arteries) are constricted by physical pressure, occluded by disease, or interrupted by injury. This redundancy of blood supply is generally termed collateral circulation. Arteries supply blood to specific areas of the brain. However, more than one arterial branch may support a region. For example, the cerebellum is supplied by the anterior inferior cerebellar artery, the superior cerebellar artery, and the posterior inferior cerebellar arteries. Venous return of deoxygenated blood from the brain Veins of the cerebral circulatory system are valve-less and have very thin walls. The veins pass through the subarachnoid space, through the arachnoid matter, the dura, and ultimately pool to form the cranial venous sinus. There are external cerebral veins and internal cerebral veins. As with arteries, specific areas of the brain are drained by specific veins. For example, the cerebellum is drained of deoxygenated blood by veins that ultimately form the great cerebral vein. External cerebral veins include veins from the lateral surface of the cerebral hemispheres that join to form the superficial middle cerebral vein.

Nourishing brain tissue The cerebral arteries provide blood to the brain, but a sufficient arterial blood pressure is required to provide an adequate supply of blood to all brain tissue. Unlike the general body blood pressure, the cerebral blood pressure and cerebral blood flow remain relatively constant, a feat of regulation made possible by rapid changes in the resistance to blood flow within cerebral vessels. Resistance is lowered, principally through changes in the diameter of the blood vessels, as the cerebral arterial pressure lowers, and resistance increases as the incoming arterial pressure increases. A complex series of nerves, including a branch of the glossopharyngeal nerve (the sinus nerve), relate small changes in the size of the carotid sinus (a dilation or enlargement of the internal carotid artery) such that if arterial pressure increases and causes the sinus to swell, the nervous impulses transmit signals to areas of the brain that inhibit the heart rate. 214

An oxygenated blood supply is critical to brain function An adequate blood supply is critical to brain function and healthy neural tissue. Physiological studies utilizing radioisotopes and other traceable markers establish that the majority of the blood originally passing through the left vertebral and left internal carotid arteries normally supply the left side of the brain, with a similar situation found on the right with the right vertebral and right internal carotid arteries. Accordingly, the left half of the brain receives its blood supply from the left internal carotid and left vertebral artery. The right half of the brain receives its blood supply from the right internal carotid and right vertebral artery. The two independent blood supplies do not normally mix or crossover except for a small amount in the posterior communicating artery (and in some cases, the arterial circle of Willis). Compensating mechanisms However, if there is some obstruction of blood flow (cerebral ischemia), there is a compensating mechanism. The two left and right supplies of blood normally do not mix in the posterior communicating artery because they are at roughly equal pressures. Even after the two vertebral arteries join to form the basilar artery prior to joining the arterial circle of Willis, the bloodstreams from the two vertebral arteries remain largely separated as though there were a partition in the channel. If there is an obstruction on one side that reduces the flow of blood, the pressures of the two sides do not remain equal and so blood from the unaffected side (at a relatively higher pressure) is able to crossover and help nourish tissue on the occluded side of the brain. The arterial circle of Willis can also permit crossover flow when the pressures are altered by an obstruction or constriction in an internal carotid or vertebral artery. In addition to crossover flow, the size of the communicating arteries and the arteries branching from the circle of Willis is able to change in response to increased blood flow that accompanies occlusion or interruption of blood supply to another component of the circle. Accordingly, oxygenated blood from either vertebral artery or either internal carotid may be able to supply vital oxygen to either cerebral hemisphere.

Vascular disorders The disorders that result from an inadequate supply of blood to the brain depend largely on which artery is occluded (blocked) and the extent of the occlusion.

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Resources BOOKS

Bear, M., et al. Neuroscience: Exploring the Brain. Baltimore: Williams & Wilkins, 1996. Goetz, C. G., et al. Textbook of Clinical Neurology. Philadelphia: W. B. Saunders Company, 1999. WEBSITES

Mokhtar, Yasser. The Doctor’s Lounge.net. “Cerebral Circulation.” May 5, 2004 (May 27, 2004). .

Paul Arthur

❙ Cerebral dominance Definition

Cerebral dominance refers to the dominance of one cerebral hemisphere over the other in the control of cerebral functions.

Description Cerebral dominance is the ability of one cerebral hemisphere (commonly referred to as the left or right side of the brain) to predominately control specific tasks. Accordingly, damage to a specific hemisphere can result in an

Key Terms Cerebral dominance The preeminence of one cerebral hemisphere over the other in the control of cerebral functions. Handedness The preference of either the right or left hand as the dominant hand for the performance of tasks such as writing.

impairment of certain identifiable functions. For example, trauma to the left hemisphere can impair functions associated with speech, reading, and writing. Trauma to the right hemisphere can result in a decreased ability to perform such tasks as judging distance, determining direction, and recognizing tones and similar artistic functions.

Cerebral dominance and handedness Cerebral dominance is also related to handedness— whether a person has a strong preference for the use of their right or left hand. More than 90% of people are righthanded and in the vast majority of these individuals, the left hemisphere controls language-related functions. In left-handed individuals, however, only about 75% have language functions predominantly controlled by the left hemisphere. The remainder of left-handed individuals have language functions controlled by the right hemisphere, or do not have a dominant hemisphere with regard to language and speech. A very small percentage of people are ambidextrous, having no preference for performing tasks with either hand. One aspect of cerebral dominance theory that has received considerable research attention is the relationship between a lack of cerebral dominance and dyslexia. Some research data suggest that indeterminate dominance with regard to language—a failure of one hemisphere to clearly dominate language functions—results in dyslexia. Evidence to support this hypothesis is, however, not uniform or undisputed. In general terms, for right-handed people the left side of the brain is usually associated with analytical processes while the right side of the brain is associated with intuitive or artistic abilities. The data to support such generalizations is, however, not uniform. The cortex is divided into several cortical areas, each responsible for separate functions such as planning of complex movements, memory, personality, elaboration of thoughts, word formation, language understanding, motor coordination, visual processing of words, spatial orientation, and body spatial coordination. The association areas

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There are three general types of disorders that can result in inadequate blood flow to the brain. Although there are pressure-compensating mechanisms in the cerebral circulation, heart disease and diseases that affect blood pressure in the body can also influence cerebral blood pressure. Sometimes people get lightheaded or dizzy when they stand up suddenly after sitting for long periods. The dizziness is often due to postural hypotension, an inadequate supply of blood to the brain due to a lowered cerebral arterial blood pressure initially caused by an obstruction to the return of venous blood to the heart. Shock can also cause a lowering of cerebral blood pressure. Disorders or diseases that result in the blockage of arteries can certainly have a drastic impact on the quality of cerebral circulation. A clot (thrombus) that often originates in plaque lining the carotid or vertebral arteries can directly obstruct blood flow in the cerebral circulation. Cerebral aneurysms, small but weakening dilations of the cerebral blood vessels, can rupture, trauma can cause hemorrhage, and a number of other disorders can directly impair blood flow. Lastly, diseases that affect the blood vessels themselves, especially the arterial walls, can result in vascular insufficiency that can result in loss of consciousness, paralysis, or death.

Cerebral hematoma

of the cortex receive and simultaneously analyze multiple sensations received from several regions of the brain. The brain is divided into two large lobes interconnected by a bundle of nerves, the corpus callosum. It is now known that in approximately 95% of all people, the area of the cortex in the left hemisphere can be up to 50% larger than in the right hemisphere, even at birth. Both Wernicke’s and the Broca’s areas (specific anatomical regions) are usually much more developed in the left hemisphere, which gave origin to the theory of left hemisphere dominance. The motor area for hand coordination is also dominant in nine of out 10 persons, accounting for the predominance of right-handedness among the population. Studies also show that the non-dominant hemisphere plays an important role in musical understanding, composition and learning, perception of spatial relations, perception of visual and other esthetical patterns, understanding of connotations in verbal speeches, perception of voice intonation, identification of other’s emotions and mood, and body language. One hindrance to the acceptance of data relating to cerebral dominance is the fact that social pressure to conform to the norm can drive some left-handed people to adopt the predominant use of their right hand. Resources BOOKS

Bear, M., et al. Neuroscience: Exploring the Brain. Baltimore: Williams & Wilkins, 1996. Tortora, G. J., and S. R. Grabowski. Principles of Anatomy and Physiology, 9th ed. New York: John Wiley and Sons Inc., 2000. PERIODICALS

White, L. E., G. Lucas, A. Richards, and D. Purves. “Cerebral Asymmetry and Handedness.” Nature 368 (1994): 197–198.

Sandra Galeotti Brian Douglas Hoyle, PhD

❙ Cerebral hematoma Definition

Cerebral hematoma involves bleeding into the cerebrum, the largest section of the brain, resulting in an expanding mass of blood that damages surrounding neural tissue.

Description A hematoma is a swelling of blood confined to an organ or tissue, caused by hemorrhaging from a break in one or more blood vessels. As a cerebral hematoma grows, 216

it damages or kills the surrounding brain tissue by compressing it and restricting its blood supply, producing the symptoms of stroke. The hematoma eventually stops growing as the blood clots, the pressure cuts off its blood supply, or both. Cerebral hematomas are categorized by their diameter and estimated volume as small, moderate, or massive. The neurologic effects produced by a cerebral hematoma are quite variable, and depend on its location, size, and duration (length of time until the body breaks down and absorbs the clot). Additional bleeding into the ventricles, which contain the cerebrospinal fluid (CSF), may occur. Blood in the CSF presents a risk for further neurologic damage. Intracerebral hematoma (ICH) is another frequently used term for the condition. The initials “ICH” may also be seen in different places denoting several related conditions—an intracerebral hematoma is due to an intracerebral hemorrhage, which is one type of intracranial hemorrhage. However, the causes and symptoms of all three are roughly the same.

Demographics The two basic types of stroke are hemorrhagic (including ICH) and ischemic (blockage in a blood vessel). Each year 700,000 people in the United States, or about 1 in 50 individuals, experience a new or recurrent stroke. Of these, about 12% are due to intracranial hemorrhage. Stroke kills an estimated 170,000 people each year in the United States, and is the leading cause of serious, longterm disability. Thirty-five percent of individuals suffering a hemorrhagic stroke die within 30 days, while the onemonth mortality rate for ischemic stroke is 10%. Stroke occurs somewhat more frequently in men than in women. Compared to whites, the incidence of first-occurrence strokes in most other ethnic groups in the United States is slightly higher, except African-Americans, whose rate is nearly twice as high. In adults, the risk of stroke increases with age. The highest risk for stroke in children is in the newborn period (especially in premature infants), with an incidence of 1 in 4000. The risk then decreases throughout childhood to a low of 1 in 40,000 in teen-agers. Twenty-five percent of strokes in children are due to intracranial hemorrhage.

Causes and symptoms The most frequent causes of intracranial hemorrhage, including ICH, are: • Hypertension-induced vascular damage • Ruptured aneurysm or arteriovenous malformation (AVM)

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Aneurysm A weakened area in the wall of a blood vessel which causes an outpouching or bulge. Aneurysms may be fatal if these weak areas burst, resulting in uncontrollable bleeding.

Hypertension Abnormally high arterial blood pressure that if left untreated can lead to heart disease and stroke.

Cerebrum The largest section of the brain, which is responsible for such higher functions as speech, thought, vision, and memory.

Ischemia A decrease in the blood supply to an area of the body caused by obstruction or constriction of blood vessels.

Hematoma A localized collection of blood, often clotted, in body tissue or an organ, usually due to a break or tear in the wall of blood vessel.

Stroke Interruption of blood flow to a part of the brain with consequent brain damage. A stroke may be caused by a blood clot or by hemorrhage due to a burst blood vessel. Also known as a cerebrovascular accident.

Hemorrhage Severe, massive bleeding that is difficult to control. The bleeding may be internal or external.

• Head trauma • Diseases that result in a direct or indirect risk for uncontrolled bleeding • Unintended result from the use of anticoagulant (anticlotting) or thrombolytic (clot dissolving) drugs for other conditions • Complications from arterial amyloidosis (cholesterol plaques) • Hemorrhage into brain tumors Preventable factors that increase the risk for stroke include chronic hypertension, obesity, high cholesterol (atherosclerosis), sedentary lifestyle, and chronic use of tobacco and/or alcohol. These factors primarily increase the risk for ischemic stroke, but play a role in ICH as well. As previously noted, a massive ICH can result in sudden loss of consciousness, progressing to coma and death within several hours. For small and moderate hemorrhages, the usual symptoms are sudden headache accompanied by nausea and vomiting, and these may remit, recur, and worsen over time. Other, more serious symptoms of stroke include weakness or paralysis on one side of the body (hemiparesis/hemiplegia), difficulty speaking (aphasia), and pronounced confusion with memory loss. Seizures are not a common symptom of ICH. Hydrocephalus—increased fluid pressure in the brain—may result if pressure from the hematoma or a clot obstructs normal circulation of the CSF. Again, the severity and type of symptoms depend greatly on the location and size of the hematoma.

Diagnosis Symptoms may indicate the possibility of an ICH, but the diagnosis can only be made by visualizing the hematoma using either a computed tomography (CT) or

magnetic resonance imaging (MRI) scan. In some cases, more sophisticated imaging methods such as functional-MRI, SPECT, or PET scans can be used to visualize damaged areas of the brain.

Treatment team An ICH producing mild symptoms might prompt a direct or referred visit to a neurologist, while individuals with more serious symptoms are first seen by hospital emergency room staff. Once the diagnosis of ICH is made, other specialists consulted or involved could include a neurosurgeon, radiologist, neurologist, and intensive care unit (ICU) staff. Long-term care might involve a psychiatrist/psychologist, dietitian, occupational/physical/speech therapists, rehabilitation specialists, and health professionals from assisted-living facilities or home-care agencies.

Treatment Initial treatments in patients who have lost consciousness involve stabilizing any affected systems such as respiration, fluid levels, blood pressure, and body temperature. In many cases, monitoring intracranial pressure (ICP) is critical, since elevated ICP poses a serious risk for coma and death. Management of elevated ICP can be attempted with medication or manipulation of blood oxygen levels, but surgery is sometimes required. The possibility of further hemorrhaging in the brain poses a serious risk, and requires follow-up imaging scans. If an ICH is detected very early, a neurosurgeon may attempt to drill through the skull and insert a small tube to remove (aspirate) the blood. Once the blood has clotted, however, aspiration becomes more difficult or impossible. Surgery to remove a hematoma is usually not advised unless it threatens to become massive, is felt to be life-threatening, or is causing rapid neurologic deterioration.

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Key Terms

Cerebral palsy

Recovery and rehabilitation

ORGANIZATIONS

Recovery and rehabilitation centers around regaining as much neurologic function as possible, along with developing adaptive and coping skills for those neurologic problems that might be permanent. Recovery from neurologic injury caused by hemorrhagic stroke is frequently long and difficult, but there are many sources of information and support available. Rehabilitation is most often done on an outpatient basis, but more serious cases may require nursing assistance at home or institutional care. Those who lapse into a coma or persistent vegetative state will need 24-hour professional care, and may take days, months, or years to recover, or they may never recover.

Clinical trials Research is under way to develop effective, safer medications and methods to both stop a hemorrhage while it is occurring, and dissolve clots within the brain once they have formed. Direct injection of a local-acting clotting agent into an expanding hematoma, or of a thrombolytic drug, such as recombinant tissue plasminogen activator (rt-PA), into the clot are two avenues of research.

Prognosis The prognosis after an ICH varies anywhere from excellent to fatal, depending on the size and location of the hematoma. However, ICH is the most serious form of stroke, with the highest rates of mortality and long-term disability, and the fewest available treatments. Only a small proportion of patients with an ICH can be given a good or excellent prognosis. Resources

Scott J. Polzin, MS, CGC

❙ Cerebral palsy Definition

Cerebral palsy is a term used to describe a group of chronic conditions affecting body movements and muscle coordination. It is caused by damage to one or more specific areas of the brain, usually occurring during fetal development or during infancy.

Description

BOOKS

Bradley, Walter G., et al., eds. “Principles of Neurosurgery.” In Neurology in Clinical Practice, 3rd ed., pp. 931-942. Boston: Butterworth-Heinemann, 2000. Victor, Maurice and Allan H. Ropper. “Cerebrovascular Diseases.” In Adams’ and Victor’s Principles of Neurology, 7th ed., pp. 881-903. New York: The McGrawHill Companies, Inc., 2001. Wiederholt, Wigbert C. Neurology for Non-Neurologists, 4th ed. Philadelphia: W. B. Saunders Company, 2000. PERIODICALS

Glastonbury, Christine M. and Alisa D. Gean. “Current Neuroimaging of Head Injury.” Seminars in Neurosurgery 14 (2003): 79-88. Mayer, Stephan A. “Ultra-Early Hemostatic Therapy for Intracerebral Hemorrhage.” Stroke 34 (January 2003): 224-229. Rolli, Michael L. and Neal J. Naff. “Advances in the Treatment of Adult Intraventricular Hemorrhage.” Seminars in Neurosurgery 11 (2000): 27-40. 218

Brain Aneurysm Foundation. 12 Clarendon Street, Boston, MA 02116. 617-723-3870; Fax: 617-723-8672. . Brain Injury Association. 8201 Greensboro Drive, Suite 611, McLean, VA 22102. 800-444-6443; Fax: 703-761-0755. . Brain Trauma Foundation. 523 East 72nd Street, 8th Floor, New York , NY 10021. 212-772-0608; Fax: 212-7720357. . National Institute on Disability and Rehabilitation Research (NIDRR). 600 Independence Ave., S.W., Washington, DC 20013-1492. 202-205-8134. . National Rehabilitation Information Center (NARIC). 4200 Forbes Boulevard, Suite 202, Lanham, MD 20706-4829. 800-346-2742; Fax: 301-562-2401. . National Stroke Association. 9707 East Easter Lane, Englewood, CO 80112-3747. 800-787-6537; Fax: 303649-1328. .

Cerebral palsy (CP) is an umbrella-like term used to describe a group of chronic disorders impairing movement control that appear in the first few years of life and generally do not worsen over time. The disorders are caused by faulty development or damage to motor areas in the brain that disrupt the brain’s ability to control movement and posture. The causes of such cerebral insults include vascular, metabolic, infectious, toxic, traumatic, hypoxic (lack of oxygen) and genetic causes. The mechanism that originates cerebral palsy involves multi-factorial causes, but much is still unknown. Cerebral palsy distorts messages from the brain to cause either increased muscle tension (hypertonus) or reduced muscle tension (hypotonus). Sometimes this tension will fluctuate, becoming more or less obvious. Symptoms of CP include difficulty with fine motor tasks (such as writing or using scissors) and difficulty maintaining balance or walking. Symptoms differ from

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Cerebral palsy

Key Terms Ataxic Muscles that are unable to perform coordinated movements due to damage to one or more parts of the brain. Contracture Chronic shortening of muscle fibers resulting in stiffness and decrease in joint mobility. Hypertonus Increased tension of a muscle or muscle spasm. Hypotonus Decreased tension of a muscle, or abnormally low muscle tone. Hypoxic Oxygen deficient. Ischemic Having inadequate blood flow. Orthotic device Devices made of plastic, leather, or metal which provide stability at the joints or passively stretch the muscles. Spasticity Increased muscle tone, resulting in involuntary muscle movements, muscle tightness, and rigidity. Teratogenic Able to cause birth defects.

person to person and may change over time. Some people with CP are also affected by other medical disorders, including seizures or mental impairment. Early signs of CP usually appear before three years of age. Infants with this disease are frequently slow to reach developmental milestones such as learning to roll over, sit, crawl, smile, or walk. Causes of CP may be congenital (present at birth) or acquired after birth. Several of the causes that have been identified through research are preventable or treatable: head injury, jaundice, Rh incompatibility, and rubella (German measles). Cerebral palsy is diagnosed by testing motor skills and reflexes, examining the medical history, and employing a variety of specialized tests. Although its symptoms may change over time, this disorder by definition is not progressive. If a patient shows increased impairment, the physician considers an alternative diagnosis.

Demographics Cerebral palsy is one of the most common causes of chronic childhood disability. About 3,000 babies are born with the disorder each year in the United States, and about 1,500 preschoolers are diagnosed with cerebral palsy during the first three years of life. In almost 70% of cases, CP is found with some other disorder, the most common being

Dan Keplinger, author of the 1999 Oscar-winning documentary “King Gimp,” sits in a wheelchair among his paintings on display at the Phillis Kind Gallery in New York. (AP/Wide World Photos. Reproduced by permission.)

mental retardation. In all, around 500,000–700,000 Americans have some degree of cerebral palsy. The prevalence of CP has remained very stable for many years. The incidence increases with premature or very low-weight babies regardless of the quality of care. Twins are also four times more likely to develop CP than single births. Despite medical advances, in some cases the incidence of CP has actually increased over time. This may be attributed to medical advances in areas related to premature babies or the increased usage of artificial fertilization techniques.

Causes and symptoms CP is caused by damage to an infant’s brain before, during or shortly after delivery. The part of the brain that is damaged determines what parts of the body are affected.

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There are a number of factors which appear to predispose a child to CP including: • Exposure of the expectant mother to certain infections like rubella, toxoplasmosis and cytomegalovirus, • Exposure of the expectant mother to certain chemicals like alcohol, cigarettes, cocaine and teratogenic (capable of causing birth defects) agents, • Severe physical trauma to the mother during pregnancy, multiple births or maternal illness, • Children who are born prematurely (less than 32 weeks) or who are very low birth weight (less than 1,500 grams or about 31⁄3 pounds), • Failure of the brain to develop properly or neurological damage to the infant’s developing brain, including hypoxia (lack of oxygen) during birth, • Bacterial meningitis and other infections, bleeding in the brain, lack of oxygen, severe jaundice, and head injury during the first few years of a child’s life. Cerebral palsy is categorized into four different groups that are characterized by different symptoms. Generally, babies that are severely affected may have obvious signs immediately following birth. Many infants do not display immediate CP symptoms. Parents are usually able to notice developmental delays, especially if they have another unaffected child. At the age of about three months, parents may notice a lack of facial expressions or that their baby does not respond to some sounds, or does not follow movement with their eyes. Certain other indicative symptoms may appear at around six months of age, including inability to lift the head or roll over and difficulty feeding. An affected child may be unable to crawl, sit, or stand without support and drooling is a common problem because of poor facial and throat muscle control. CP symptoms depend on the individual and the type of CP and, in particular, whether or not there is a mixed form of the condition. The four main categories of cerebral palsy are: • Spastic CP: Children with spastic CP have increased muscle tone. Their muscles are stiff and their movements can be awkward. Seventy to eighty percent of people with this disease have spasticity. Spastic CP is usually described further by what parts of the body are affected. In spastic diplegia, the main effect is found in both legs. In spastic hemiplegia, one side of the person’s body is affected. Spastic quadriplegia affects a person’s whole body (face, trunk, legs, and arms). • Athetoid or dyskinetic CP: Children with athetoid CP have slow, writhing movements that they cannot control. The movements usually affect a person’s hands, arms, feet, and legs. Sometimes the face and tongue are affected and the person has a hard time talking. Muscle

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tone can change from day to day and can vary even during a single day. Ten to twenty percent of people with CP have the athetoid form of the condition. • Ataxic CP: Children with ataxic CP have problems with balance and depth perception. They might be unsteady when they walk. They might have a hard time with quick movements or movements that need a lot of control, like writing. Controlling their hands or arms when they reach for something is often difficult. People with ataxic CP can have increased or decreased muscle tone. • Mixed CP: Some people have more than one type of CP, but this is most often a mixture of spasticity and athetoid movements, with tight muscle tone and involuntary reflexes.

Diagnosis Diagnosing CP in an infant is often a difficult and slow process that takes time to establish with certainty, as there other health problems that can mimic the condition. The physician may suspect that the infant has CP because of a history of difficulties at birth, seizures, feeding problems or low muscle tone. Detailed medical and developmental history, including the history of the pregnancy and delivery, medications taken by the mother during fetal development, infections and fetal movement are all considered. A detailed family history, including the mother’s history of miscarriage, relatives with similar conditions, ethnic background, and consanguinity (marriage between close blood relatives) can also prove helpful. The child’s physician will perform a thorough physical examination and may order vision and hearing testing. Infants suffering from brain injury are often slow to reach developmental milestones including rolling over, sitting up, crawling, walking and talking. Healthcare professionals are often hesitant to reach an early diagnosis because the child may recover and they may use other, less emotive terms in labeling the condition such as: neuromotor dysfunction, developmental delay, motor disability, static encephalopathy and central nervous system dysfunction. Physicians must test the child’s motor skills, using many of the techniques outlined above and looking for evidence of slow development, abnormal muscle tone, and unusual posture. Healthcare professionals will move slowly and carefully towards a positive diagnosis only after eliminating all other possible causes of the child’s condition. Neuroimaging studies can help to evaluate brain damage and to determine those at risk of developing CP. No study exists to support definitive diagnosis of CP. Computed tomography (CT) scans provide information to help diagnose congenital malformations and intracranial hemorrhages in the infant. Magnetic resonance imaging

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Ultrasound in the neonate (newborn) provides information about the structures of the brain as well as diagnostic information on possible hemorrhage or hypoxicischemic (lack of oxygen) injury. Evoked potentials are used to evaluate the anatomic pathways of the nerves responsible for hearing and vision. Electroencephalogram (EEG) is useful in evaluating severe hypoxic-ischemic injury.

Treatment team A neurologist may help to differentiate cerebral palsy from other neurological disorders. Consultation with a neurologist also may be helpful in treatment of patients with seizures. Pulmonologists (lung specialists) may help treat the patient with bronchopulmonary dysplasia or frequent aspiration pneumonia. Orthopedic surgery consultation may be needed to help correct any structural deformities. An ophthalmologist may be indicated to follow up with any patient experiencing visual deficits. Audiologists help screen for hearing deficits. A gastroenterologist (specialist on digestive disorders) may help with reflux and constipation and may be helpful in coordinating feedings to regulate weight gain or weight loss if needed. A periodic nutrition consultation is important to make sure the child does not suffer from growth failure or nutritional deficiencies.

Treatment Drug therapy is used for those who have seizures associated with CP. Anticonvulsant medications are usually very effective in preventing seizures associated with CP. Drugs are also used to control spasticity in some cases. Medications used most often are diazepam, a general relaxant of the brain and body, baclofen, which blocks signals sent from the spinal cord to contract the muscles, and datrolene, which interferes with the process of muscle contraction. These drugs are used for short periods, but long-term control of spasticity is more difficult to achieve. Persons with athetoid CP are sometimes given drugs to help reduce abnormal movements, usually anticholinergics. Anticholinergics reduce the activity of acetylcholine, a chemical messenger that helps some brain cells communicate and trigger muscle contraction. Physicians may inject drugs directly into a muscle to reduce spasticity for a short period. Surgery is used when muscle contractures are severe enough to create problems in movement. The surgeons lengthen the muscle that is too short. Lengthening a muscle usually makes it weaker, so surgery for contractures is

usually followed by an extended recovery and therapy period. To reduce spasticity in the legs, surgery called selective dorsal root rhizotomy sometimes proves effective. It reduces the amount of stimulation that reaches leg muscles by the nerves.

Recovery and rehabilitation Cerebral palsy cannot be cured. Treatment can, however, help a person take part in family, school, and work activities as much as possible. There are many treatments, including physical therapy, occupational therapy, medicine, operations, and orthotic devices that help maintain the highest possible state of wellness and activity. Specialized Therapies Physical therapy improves infant-caregiver interaction, gives family support, and supplies resources for parental education, as well as promoting motor and developmental skills. Physical therapists teach the parent or caregiver exercises or activities necessary to help the child reach his or her full potential. Daily range of motion (ROM) exercises are important to prevent or delay contractures (fixed, rigid muscles) secondary to spasticity, and to maintain mobility of joints and soft tissues. Stretching exercises are performed to increase motion. Progressive resistance exercises also increase strength. Age-appropriate play and adaptive toys and games using the desired exercises are important to elicit the child’s full cooperation. Strengthening knee extensor muscles helps to improve crouching and stride length. Postural and motor control training is important following the normal developmental sequence of children (i.e., achieve head and neck control if possible before advancing to trunk control). Occupational therapists keep the child’s developmental age in mind and use adaptive equipment as needed to help attain these milestones. For example, if a child is developmentally ready to stand and explore the environment, but is limited by lack of motor control, a stander or modified walker is used. Performance based upon previous success is encouraged to maintain the child’s interest and cooperation. Assistive devices and durable medical equipment help attain function that may not be possible otherwise. Orthotic devives frequently are required to maintain functional joint position especially in persons who are non-ambulatory. Frequent reevaluation of orthotic devices is important as children quickly outgrow them and can develop skin irritation from improper use of orthotic devices. Recreational therapy, especially hippotherapy (horseback riding therapy) is frequently a well-liked activity of parents and patients alike to help with muscle tone, range

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(MRI) is most useful after two to three weeks of life, and is also used to detect brain disease in an older child.

Cerebral palsy

can be implemented to help improve swallowing and communication. Those patients with athetoid CP may benefit the most from speech therapy, as most have normal intelligence and communication is an obstacle secondary to abnormal muscle movements that affect their speech. Adequate communication is probably the most important goal for enhancing function in the athetoid CP patient.

Chromosome 2 25 24 2

ETM2: Essential tremor

Oculo-digito-esophago-duodenal syndrome

23 22 21 16

MSH2: Colon cancer

Clinical trials

CSNU: Cystinuria

As of mid-2004, there were numerous open clinical trials for the study and treatment of cerebral palsy, including:

15 1 14 13

ALMS1: Alstrom syndrome

• “Botulinum Toxin (BOTOX) for CP,” “Relaxation Training to Decrease Pain and Improve Function in Adolescents with CP,” and “Constraint-based Therapy to Improve Motor Function in Children with CP,” sponsored by the National Institute of Child Health and Human Development (NICHD),

12 11

p q

11 1 12 13

• “Classification of CP Subtypes,” “Eye-Hand Coordination in Children with Spastic Diplegia,” “Beneficial Effects of Antenatal Magnesium Sulfate (BEAM Trial),” and “Brain Control of Movements in CP,” sponsored by National Institute of Neurological Disorders and Stroke (NINDS),

14

21

2

22 23 24

• Study of Tongue Pressures, sponsored by Warren G. Magnuson Clinical Center.

Spastic cerebral palsy

Updated information about these clinical trials can be found at the National Institutes of Health website for clinical trials at www.clinicaltrials.gov.

31

32

Prognosis

33 34 35

PAX3: Waardenburg syndrome

36 37

Cerebral palsy, on chromosome 2. (Gale Group.)

of motion, strength, coordination, and balance. Hippotherapy also offers many potential cognitive, physical, and emotional benefits. Incorporation of play into all of a child’s therapies is important. The child should view physical and occupational therapy as fun, not work. Caregivers should seek fun and creative ways to stimulate children, especially those who have decreased ability to explore their own environments. Many children with dyskinetic CP have involvement of the face and oropharynx causing difficulty swallowing properly, drooling, and speech difficulties. Speech therapy

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The prognosis of persons with CP varies according to the severity of the disorder. Some children have only mild problems in muscle tone and no problems with daily activities, while others are unable to purposefully move any part of the body. Regression, or worsening of long-term symptoms, is not characteristic of CP. If regression occurs, it is necessary to look for a different cause of the child’s problems. In order for a child to be able to walk, a major cascade of events in motor control have to occur. A child must be able to hold up his head before he can sit up on his own, and he must be able to sit independently before he can walk on his own. It is generally assumed that if a child is not sitting up by himself by age four or walking by age eight, he will never be an independent walker. But a child who starts to walk at age three will certainly continue to walk unless he has a disorder other than CP. In people with severe CP, motor problems often lead to medical complications, including more frequent and serious infections, severe breathing problems, feeding intolerance, and skin breakdown. These medical complications

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Epilepsy also occurs in about a third of children with CP and is more frequent in patients with spastic quadriplegia or mental retardation. Cognitive impairment occurs more frequently in CP than in the general population, and mental delays or some form of learning disability has been estimated to occur in over two thirds of CP cases. Resources BOOKS

Anderson, Mery Elizabeth, Dineen Tom. Taking Cerebral Palsy to School. St. Louis: Jayjo Books, 2000. Mechan, Merlin L. Cerebral Palsy. Austin, TX: Pro-Ed Publishers, 2002. Pincus, Dion. Everything You Need to Know About Cerebral Palsy (Need to Know Library). New York: Rosen Publishing Group, 1999. PERIODICALS

Darrah, J., et al. “Conductive education intervention for children with cerebral palsy: an AACPDM evidence report.” Dev Med Child Neurol 46 (March 2004): 187–203. OTHER

“Cerebral Palsy—Facts & Figures.” United Cerebral Palsy. (May 1, 2004). . “NINDS Cerebral Palsy Information Page.” National Institute of Neurological Disorders and Stroke. (May 1, 2004). . ORGANIZATIONS

March of Dimes Birth Defects Foundation. 1275 Mamaroneck Avenue, White Plains, NY 10605. (914) 428-7100 or (888) 663-4637; Fax: (914) 428-8203. askus@ marchofdimes.com. . United Cerebral Palsy (UCP). 1600 L Street, NW, Suite 700, Washington, DC 20036. (202) 776-0406 or (800) USA5UCP (872-5827); Fax: (202) 776-0414. [email protected]. .

Francisco de Paula Careta Iuri Drumond Louro

❙ Channelopathies Definition

Channelopathies are inherited diseases caused by defects in cell proteins called ion channels. Channelopathies include a wide range of neurologic diseases, including periodic paralysis, congenital myasthenic syndromes, malignant hypothermia, a form of Charcot-Marie-Tooth disease, and several other disorders. Cystic fibrosis and long Q-T syndrome, which are not neurological diseases, are also types of channelopathy.

Description Cells of the body, including nerve and muscle cells, are surrounded by thin coverings called membranes. Embedded in these membranes are a large and varied set of proteins that control the movement of materials across the membrane, in and out of the cell. One major type of material that crosses through such proteins are called ions, and the proteins that transport them are called ion channels. Ions perform many different functions in cells. In neurons (nerve cells), they help transmit the electrical messages that allow neurons to communicate with each other, and with muscle cells. In muscle cells, they allow the muscle to contract. When the ion channels are defective, these activities may be disrupted.

Inheritance The proteins responsible for channelopathies are made by genes, and defects in genes are the cause for the diseases. Genes are inherited from both parents. If two defective copies of a gene are needed in order for a person to develop the disease, this is known as a recessive inheritance pattern. Two parents, each of whom carry one defective copy, have a 25% chance with each pregnancy of having a child with the disease. If only one defective copy of the gene is needed in order to develop the disease, this is known as a dominant inheritance pattern. A single parent who carries the disease gene (and likely has the disease as well) has a 50% chance with each pregnancy of having a child with the disease.

Types of Channelopathies

Cerebrovascular accident (CVA) see Stroke Cervical disc herniation see Disc herniation Cervical radiculopathy see Radiculopathy

Periodic paralysis A person with periodic paralysis experiences sudden onset of weakness, which gradually subsides, only to return again later. Two forms of periodic paralysis exist, termed “hyperkalemic,” referring to the excessively high levels of potassium in the blood which can trigger attacks,

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can lead to frequent hospitalizations and a shortened life expectancy.

Charcot-Marie-Tooth disorder

and “hypokalemic,” in which excessively low levels of potassium are the culprit. Each is caused by different genetic mutations of a potassium ion channel, and both exhibit the dominant inheritance pattern. Onset is usually in childhood for the hyperkalemic form, and childhood to adulthood for the hypokalemic form. Dietary restrictions can reduce the frequency of attacks of both forms, with a high-carbohydrate, low-potassium diet for the hyperkalemic form, and a low-carbohydrate, high-potassium diet for the hypokalemic form. Congenital myasthenic syndromes Congenital myasthenic syndromes are a group of related disorders caused by inherited defects in the acetylcholine receptor. This protein sits on the surface of muscle cells; when a nearby neuron releases the chemical acetylcholine, it binds to the receptor, causing the muscle to contract. Defects cause myasthenia (“muscle weakness”) and fatigue, and may be life-threatening in some individuals. Most forms display the recessive inheritance pattern. Onset is in infancy. Treatment usually includes the drug mestinon, which blocks the breakdown of the acetylcholine after it is released, prolonging its action, and another drug, called 3,4-DAP, which increases the amount of acetylcholine released. Malignant hyperthermia Malignant hyperthermia is caused by mutations in the gene for a membrane protein inside the muscle cell, called the ryanodine receptor, which controls calcium ion movement within the muscle. Another form is due to mutation in a different muscle protein controlling calcium. Malignant hyperthermia is usually triggered by exposure to certain kinds of anesthetics or muscle relaxants. It causes a dangerous increase in the rate of activity within the muscle, and a sharp rise in temperature, leading to a cascade of crises which may include severe damage to muscle cells, heart malfunction, swelling of tissues including the brain, and death. It is treated with dantrolene, an antispasticity medication that blocks calcium ion movement in the muscle. Awareness of the condition has led to better screening for it among anesthesia patients and a significant reduction in mortality. X-linked Charcot-Marie-Tooth disease X-linked Charcot-Marie-Tooth disease (CMTX) is caused by a defect in connexin 32. This protein forms connections between adjacent cells, allowing ions to flow between them. The cells affected are those that surround neurons and provide their electrical insulation. Outside the brain and spinal cord (together called the central nervous system, or CNS), this job is performed by Schwann cells. 224

Inside the CNS, the insulating cells are called oligodendrocytes. Like other forms of CMT, CMTX causes slowly progressing muscle weakness in the distal muscles (those furthest away from the body center), including the hands and feet. There may also be decreased sensation in the extremities. CMTX is inherited on the X chromosome, of which males have one and females have two. For this reason, CMTX usually affects males more severely than females because they have only one X chromosome, and therefore lack a second normal copy of the gene. Resources WEBSITES

Muscular Dystrophy Association. . Charcot-Marie-Tooth Association. .

Richard Robinson

❙ Charcot-Marie-Tooth disorder Definition

The name Charcot-Marie-Tooth disorder (CMT) refers to a group of hereditary diseases, all involving chronic motor and sensory neuropathies. Drs. Charcot and Marie of France, and Dr. Tooth of England first described the disorder in 1886 when they found patients with progressive muscle weakness and muscle loss in their feet and lower legs. Over time, this weakness progressed to their hands and forearms. More is now known about the numerous disease subtypes, including their complex genetics and inheritance patterns.

Description Charcot-Marie-Tooth disorder is also known by the names hereditary motor and sensory neuropathy, and peroneal muscular atrophy. A person with CMT often has distal muscle weakness and atrophy that involves the feet, legs, and hands. Many people with CMT are diagnosed later in life as adults. However, diagnosis can happen as early as the first to third decade of life when there is a family history of CMT. The muscle weakness may begin painlessly, symmetrically, and slowly. Many CMT subtypes seem similar and may only be identified through further neurological or genetic testing. Learning problems are not commonly associated with CMT, but psychological issues from living with progressive muscle weakness can occur. Only some rare X-linked forms of CMT involve mental retardation or deafness as

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Atrophy Wasting or loss of tissue.

Motor Having to do with movement.

Biopsy Process of removal of tissue for study.

Mutation A change in the order of deoxyribonucleic acid (DNA) bases that make up genes.

Chronic Ongoing and long-term. Distal Situated away from the center of the body, like the legs and hands. Duplication Extra genetic material due to a duplicate copy. Electromyography Testing that shows the electrical activity associated with muscle movements and actions. Gait The way in which one walks.

occasional symptoms, but these are not typical of classical CMT.

Demographics CMT is the most common genetic cause of neuropathy. It is estimated to affect between one in 2,500 to one in 5,000 people, with most of them having CMT type 1 (CMT1). About 20% of people who come to neuromuscular clinics with a chronic peripheral neuropathy have some form of CMT. The condition affects people of all ethnic groups worldwide. Most forms affect males and females equally, with the exception of the X-linked form, which usually affects males more severely than females. As of 2004, numerous genes have been found responsible for various subtypes of CMT. Genetic testing is available for some types. For other types, genetic testing is not yet available.

Causes and symptoms Mutations in several genes cause the various types of CMT to occur. The most common form of the disorder, CMT1A, is caused by duplication in the peripheral myelin protein 22 (PMP22) gene. In these cases, the PMP22 gene is too active from the extra genetic material, so it makes too much myelin protein. The correct amount of myelin protein is important for normal muscle strength and movement, so the extra amount can cause these problems. CMT is inherited in many ways, as seen by varying family histories of the condition. CMT1 and CMT2 are typically inherited in an autosomal dominant manner. This means that an affected individual has a 50/50 chance of passing a disease-causing mutation to his or her children,

Nerve conduction study Testing that shows electrical impulse activity along nerves. Neuropathy Term for any disorder affecting the nervous system or cranial nerves. Peroneal Related to the legs. Pes cavus A highly arched foot. Scoliosis Curving of the spine bones. Sensory Related to the senses, or the ability to feel.

regardless of gender. In these cases, a strong family history of the condition may be seen. CMT4 and some forms of CMT2 are inherited in an autosomal recessive manner. This means that an affected individual has parents who each carry the CMT gene. These parents run the risk of having a child with CMT with every pregnancy. CMT is also inherited in an X-linked manner, and the most common type is called CMTX. Women may be carriers of this type. They are usually more at risk to have affected sons. Daughters may be carriers and they may or may not show milder symptoms. The neurological symptoms in CMT can progress slowly, but may become problematic over time. Muscle weakness is usually found first in the foot and lower leg muscles. It can eventually include the upper leg and hips in severely affected people. Since the middle of the legs are usually stronger, most people with CMT can still usually walk with the aid of ankle splints. Some early signs of CMT may be gait abnormalities, or clumsiness in running. Many people with CMT develop pes cavus with very high arches in their feet, and this can be associated with curled-up toes. Loss of nerve functioning can lead to the inability to notice very hot and cold sensations, or the sensation of touch. Upper limb muscles may become weaker, and this includes the hands and forearms. Due to this, people may have difficulty with fine motor tasks like writing. People with more advanced CMT may develop bone changes, like scoliosis. This may cause back pain if it is very severe. A specific sign of CMT1A is the “onion bulb” formation in muscular nerves. Nerves with repeated myelination and demyelination (due to abnormalities in the

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Key Terms

Charcot-Marie-Tooth disorder

PMP22 gene) may eventually take on the shape of an onion bulb, which is how the finding was named.

Diagnosis Until the discovery of the CMT genes, the diagnosis of the condition was made on a clinical basis. The difficulties lie in the similarities with other neuropathies like hereditary neuropathy with liability to pressure palsies (HNPP) and those associated with disorders like alcoholism, drug dependence, and diabetes. An important first step to diagnosing CMT is taking a careful family history. A positive family history is an indicator that the neuropathy may be hereditary. Additionally, the pattern of affected individuals can give clues about the inheritance type in the family. Carefully documenting the timing of symptoms is also important. Only a minority of people with CMT seek a medical opinion in childhood, since most are diagnosed later in life. An exception might be the highly informed family in which there is a strong history of the condition. Skeletal signs like pes cavus and scoliosis occur in hereditary neuropathies, but tend to show up when the symptoms begin early. They may be absent when the onset is later in life, even in CMT. This may be an important clue when attempting to diagnose CMT. CMT may also include symptoms like mental retardation and hearing loss, as seen in some rarer X-linked forms. A slow progression of symptoms is typical of CMT. Some hereditary neuropathies, like HNPP, may have periods of severe symptoms that get better and then worsen later. Again, careful documentation of symptoms is important to diagnose CMT. Some signs of CMT are found through electrophysiological studies, like electromyography (EMG) and nerve conduction velocity (NCV) testing. EMG results are usually abnormal, and NCV studies may show slowed nerve conduction, a sign of muscle weakness. Those with CMT type 1 usually show severe slowing in NCV studies, and type 2 is associated with mild or no slowing. EMG and NCV studies are very important tools for physicians to use when thinking of a hereditary neuropathy. These are often abnormal, with reduced NCV values. A nerve biopsy is rarely necessary to pinpoint a specific type of CMT, because onion-bulb abnormalities are a sign of CMT1A. It may still be difficult to diagnose CMT with electrophysiological test results and clinical information. The results from testing may help to determine which genetic testing to pursue. Genetic testing is useful for confirming a clinical diagnosis or for family testing when there is an identified CMT gene mutation in the family. As of 2004,

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genetic testing for CMT type 1 is more available than testing for CMT type 2. Genetic testing is not perfect and results can be tricky to interpret. An informative test result is one that identifies a known mutation in a CMT gene, and this confirms that the person has CMT. A negative test result means a mutation was not found in the gene. This either means that the tested individual does not have CMT, or has a mutation that cannot be found through testing. It may also mean the individual has a different type of CMT or another disorder altogether. Medical geneticists and genetic counselors can be very helpful in interpreting complex genetic test results.

Treatment team Treatment for people with CMT is often dependent upon symptoms. A multi-disciplinary team and approach can be helpful. A treatment team may include a neurologist, medical geneticist, genetic counselor, orthopedic surgeon, otolaryngologist, physical therapist, occupational therapist, social worker, physiatrist, neuropsychologist, and a primary care provider. Oftentimes there are pediatric specialists in these fields who aid in the care for children. The key is good communication between the various specialists to coordinate medical care.

Treatment There is no cure for Charcot-Marie-Tooth disorder. No specific treatment is known to reverse, slow, or stop the progressive nature of the disease. In order to keep flexibility and muscle length in the ankles and feet, daily stretching of the heel cords can be helpful. Special shoes with ankle and orthopedic inserts may help to improve walking and movement. Corrective surgery by an orthopedic surgeon is required in some cases. Others need forearm crutches or canes to keep stable while walking, but fewer than 5% of people with CMT need wheelchair assistance. Splints, specific exercises, orthopedic devices, and sometimes surgery are needed to keep hands functioning well. Certain medications can be helpful for people with CMT, while others should be avoided because they can cause nerve damage. Examples of drugs to be avoided include alcohol, high doses of vitamins A and D, penicillin, taxol, and certain chemotherapy medications (vincristine, cisplatin). For overall health, a good diet and regular exercise are recommended. Exercise is particularly important because it keeps muscles functioning and maintains endurance levels.

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Rehabilitation can be ongoing in CMT, particularly if the muscle weakness has progressed considerably. Since the disorder does not typically get better with time, physical therapy and strength maintenance is very important. The disease’s early stages may not cause problems for walking or daily activities, but over time it can greatly impact a person’s life. Physical therapy may be relatively infrequent early on, but may increase as time goes on. Children may have difficulty with tasks in school, such as writing and other fine motor skills. Occupational therapists, often available at school, are helpful in these situations. Overall, a person’s time spent in recovery and rehabilitation is variable. Specialists in physical medicine and rehabilitation can be helpful in coordinating a plan to help someone retain his or her strength for as long as possible.

Prognosis Prognosis for someone with Charcot-Marie-Tooth disorder is unique to the person. The severity of the symptoms can vary greatly, even within the same family. Those who develop the disease as children may have more severe muscle weakness by the time others first see signs of the disease. However, only about 5% of people with CMT need wheelchairs at any point in their lives. CMT is not considered a fatal disease. Symptoms are chronic and progressive, and can negatively impact a person’s life. Genetic testing now helps identify people before they even develop symptoms, so personalized medical care can begin as early as possible. This has helped to reduce the risk of complications and increase the quality of life for many. Medical screening may be further tailored to the individual as scientific studies identify medical complications associated with specific CMT mutations in families.

Special concerns Due to specific muscular weakness and difficulty with fine motor tasks, careful career and job consideration is helpful for people with CMT.

PERIODICALS

Bell, Christine, and Neva Haites. “Genetic Aspects of CharcotMarie-Tooth Disease.” Archives of Disease in Childhood (April 1998) 78: 296–300. Benstead, Timothy J., and Ian A. Grant. “Charcot-Marie-Tooth Disease and Related Inherited Peripheral Neuropathies.” Canadian Journal of Neurological Sciences (2001) 28: 199–214. Berciano, Jose, and Onofre Combarros. “Hereditary Neuropathies.” Current Opinion in Neurology (2003) 16: 613–622. Pareyson, Davide. “Diagnosis of Hereditary Neuropathies in Adult Patients.” Journal of Neurology (2003) 250: 148–160. Vallat, Jean-Michel. “Dominantly Inherited Peripheral Neuropathies.” Journal of Neuropathology and Experimental Neurology (July 2003) 62(7): 699–714. WEBSITES

National Institute of Neurological Disorders and Stroke. (March 30, 2004). . Online Mendelian Inheritance in Man. (March 30, 2004). . ORGANIZATIONS

Charcot-Marie-Tooth Association. 2700 Chestnut Street, Chester, PA 19013-4867. (800) 606-CMTA; Fax: (610) 499-9267. [email protected]. . CMT World. P.O. Box 601, Hillsburgh, Ontario N0B 1Z0, Canada. (519) 855-6376; Fax: (519) 855-6746. [email protected]. . Muscular Dystrophy Campaign U.K. 7-11 Prescott Place, London SW4 6BS, U.K. +44 (0)171-720-8055; Fax: +44 (0)171-498-0670. [email protected]. .

Deepti Babu, MS, CGC

Chiari malformation see Arnold-Chiari malformation

Resources

❙ Cholinergic stimulants

BOOKS

Parker, James N., and Philip M. Parker. The Official Patient’s Sourcebook on Charcot-Marie-Tooth Disorder: A Revised and Updated Directory for the Internet Age. San Diego: Icon Health Publishers, 2002. Parry, Gareth J. Charcot-Marie-Tooth Disorders: A Handbook for Primary Care Physicians. DIANE Publishing Co., 1995.

Definition

Cholinergic stimulants are a class of drugs that produce the same effects as those of the body’s parasympathetic nervous system. Cholinergic drugs are used for a variety of purposes, including the treatment of myasthenia gravis and during anesthesia.

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Recovery and rehabilitation

Cholinergic stimulants

Purpose The parasymapthetic nervous system is responsible for conserving and restoring energy in the body by regulating day-to-day functions such as digestion, sphincter muscle relaxation, salivation, and reducing heart rate and blood pressure. Nerve impulses in the parasympathetic nervous system are transmitted from one nerve junction to another with the help of acetylcholine, the most common neurotransmitter in the parasympathetic nervous system. Cholinergic drugs are drugs that affect the levels of acetylcholine at the nerve junction. Cholinergic stimulants result in increased acetylcholine accumulation at the neuromuscular junction and prolong its effect. Cholinergic stimulant drugs are used in the diagnosis and treatment of myasthenia gravis, a disorder of nerve impulse transmission at the neuromuscular junction, resulting in severe muscle weakness. Cholinergic stimulants are also used in surgery to reduce urinary retention and to counteract the effects of some muscle relaxant medications given during anesthesia.

Description Cholinergic stimulant drugs include edrophonium chloride, (brand name, Tensilon), neostigmine (Prostigmine), piridogstimina (Mestinon), and ambenonium chloride (Mytelase). Cholinergic stimulants are available in tablet, syrup, time-release tablet, and injectable forms.

Recommended dosage Cholinergic stimulants are given in varying dosages according to the reason for use. In the treatment of myasthenia gravis, cholinergic stimulant dosages are tailored to the individual person. Patients are encouraged to keep a diary and record their response to each dose during the initial treatment period, as well as during periods of increased muscle weakness, stress, and other illness, as these conditions frequently require adjustments in dosage.

Precautions Cholinergic stimulant drugs may not be suitable for persons with asthma, heart block or slow heart rate, epilepsy, hyperactive thyroid gland, bladder obstruction, gastrointestinal tract obstruction, or stomach ulcer. Patients should notify their physicians if they have any of these conditions before taking these drugs.

Side effects The adverse effects of cholinergic stimulants include mostly rash and digestive system complaints, including queasiness, loose stools, nausea, vomiting, abdominal cramps, muscle pain, increased salivation, increase in 228

Key Terms Acetylcholine The neurotransmitter, or chemical, that works in the brain to transmit nerve signals involved in regulating muscles, memory, mood, and sleep. Myasthenia gravis A chronic autoimmune disease characterized by fatigue and muscular weakness, especially in the face and neck, that results from a breakdown in the normal communication between nerves and muscles caused by the deficiency of acetylcholine at the neuromuscular junction. Neuromuscular junction The junction between a nerve fiber and the muscle it supplies. Neurotransmitter Chemical that allows the movement of information from one neuron across the gap between the adjacent neuron. Parasympathetic nervous system A branch of the autonomic nervous system that tends to induce secretion, increase the tone and contraction of smooth muscle, and cause dilation of blood vessels.

stomach acid production, and diarrhea. Rare and potentially more serious side effects include reduced heart rate, possibly leading to cardiac arrest, and weak, shallow breathing.

Interactions Certain antibiotics, especially neomycin, streptomycin, and kanamycin, can exacerbate the effects of some cholinergic stimulants. These antibiotics should be used with caution by people with myasthenia gravis. Resources BOOKS

Henderson, Ronald E. Attacking Myasthenia Gravis. Seattle: Court Street Press, 2002. Staff. The Official Patient’s Sourcebook on Myasthenia Gravis: A Revised and Updated Directory for the Internet Age. San Diego: Icon Health Publications Group Int., 2002. OTHER

“Myasthenia Gravis Fact Sheet.” National Institute of Neurological Disorders and Stroke. February 11, 2004 (May 22, 2004). . “Tensilon Test.” Medline Plus. National Library of Medicine. May 14, 2004 (May 22, 2004). . ORGANIZATIONS

Myasthenia Gravis Foundation of America, Inc. 5841 Cedar Lake Road Suite 204, Minneapolis, MN 55416. (952)

GALE ENCYCLOPEDIA OF NEUROLOGICAL DISORDERS

Adrienne Wilmoth Lerner

❙ Cholinesterase inhibitors Definition

Cholinesterase inhibitors are a group of drugs prescribed to treat symptoms resulting from the early and middle stages of Alzheimer disease.

Key Terms Acetylcholine The neurotransmitter, or chemical that works in the brain to transmit nerve signals, involved in regulating muscles, memory, mood, and sleep. Alzheimer disease A neurological disorder characterized by slow, progressive memory loss due to a gradual loss of brain cells. Neurotransmitter Chemicals that allow the movement of information from one neuron across the gap between the adjacent neuron.

Purpose Cholinesterase inhibitors are drugs that block the activity of an enzyme in the brain called cholinesterase. Cholinesterase breaks apart the neurotransmitter acetylcholine, which is vital for the transmission of nerve impulses. Cholinesterase inhibitors are used to reduce the action of cholinesterase, thereby making more acetylcholine available to nerve cells in the brain. For normal nerve-to-nerve communication to occur, the excess acetylcholine must be dissolved following the transmission of a nerve impulse. This is the normal function of cholinesterase. This enzyme dissolves acetylcholine into its component molecules; acetate and choline. These building blocks can then be recycled to form more acetylcholine for the next round of nerve signal transmission. In disorders such as Alzheimer disease, Lewy body disease, and vascular dementia, the production of acetylcholine is decreased. As a result, nerve communication is less efficient, with consequent problems of memory and other brain and body functions. The use of cholinesterase inhibitors impedes the normal enzymatic breakdown of the little acetylcholine that is present. Although improved nerve function results with the use of cholinesterase inhibitors, the damage to brain cells caused in Alzheimer disease cannot be halted or reversed.

Description As of mid-2004, there are four types of cholinesterase inhibitors that are available. These include donepezil (Aricept®), rivastigmine (Exelon®), galantamine (Reminy®), and tacrine (Cognex®). Tacrine is not available for use in Canada. Donepezil was approved for use in the United States by the U.S. Food and Drug Administration (USFDA) in 1996. It is marketed by Pfizer as Aricept®. Rivastigmine received USFDA approval in 2000 and is sold by Novartis Pharmaceuticals as Exelon®. Galatamine received its

USFDA approval in 2001 and is marketed in the U.S. as Reminyl® by Jassen Pharmaceuticals and Ortho-McNeil. Pointing out the importance of the natural world in providing therapeutic compounds, galatamine is extracted from the bulbs of daffodils. Finally, the drug tacrine is the oldest of the cholinesterase inhibitors, having received USFDA approval in 1993. Its use has declined due to incidents of serious side effects that include reversible liver damage. Cholinesterase inhibitors are typically used to treat the early and middle stage symptoms of diseases such as Alzheimer’s. This is because the deterioration in the production of acetylcholine accelerates over time, as more and more brain cells become damaged. Thus, the best chance to achieve a benefit for a person lies at the beginning of the disease path. The benefits of cholinesterase inhibitors are judged by three patterns of the symptoms. In the early stages of Alzheimer disease, cholinesterase inhibitors may improve a person’s condition, resulting in improvement of symptoms. As the disease progresses, cholinesterase inhibitors may act to stabilize the symptoms. Finally, the symptoms continue to worsen, but at a rate that is slower than would occur if the drug(s) were not taken. One symptom that benefits from the use of cholinesterase inhibitors is called cognition. Cognition encompasses memory, language, and orientation (knowing the date, time, and a proper sense of direction). By improving, or at least retarding the rate of loss of cognition, the drugs can improve a person’s quality of life. The benefits bestowed by cholinesterase inhibitors last only as long as effective levels of the drugs are present. Discontinuing the drug leads the return of symptoms within weeks. Studies that have charted the time course of cognitive changes after taking the various cholinesterase inhibitors have demonstrated that improvements tend to peak about

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545-9438 or (800) 541-5454; Fax: (952) 646-2028. [email protected]. .

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three months after the particular drug is first taken. After that time, a person’s mental condition slowly begins to decline back to their starting point over the next six to nine months. If the drug continues to be taken, the cognitive decline becomes slower than in people who do not take the medication.

Recommended dosage The recommended dosage of cholinesterase inhibitors varies with the approving agency in a particular country. But, dosages tend not to vary appreciably. The maximum daily dose of donepezil is normally 5–10 milligram (mg). This dose is taken just once a day, either in the morning or in the evening. The maximum daily dose of rivastimine is 6–12 mg. The drug is taken twice a day with meals (typically breakfast and dinner). The maximum daily dose of galantamine is 16–24 mg, and it is also taken twice a day with meals.

Precautions As with any prescription drug, the recommended daily dosage and schedule for the drugs should not be changed independent of a physician’s notification. Neither should someone stop taking cholinesterase inhibitors without seeking advice from a physician.

Side effects Cholinesterase inhibitors can cause side effects. These are usually relatively minor, and constitute problems in digesting food, loss of appetite, nausea, vomiting, abdominal pain, and diarrhea. Not everyone will experience each discomfort, and the severity of the side effects can vary from person to person, depending on their tolerance to the discomfort. The drugs can vary in the severity of side effects caused. For example, rivastigmine produces greater weight loss and degree of nausea that the other drugs. Less commonly, cholinesterase inhibitors can slow the heartbeat, cause dizziness, fainting, insomnia, fatigue, and produce muscle cramps in the legs. In general, the side effects tend to be mild and lessen after a drug has been taken for a few weeks. A notable exception is tacrine, which can cause liver damage. Periodic blood testing in order to monitor enzymes that relate to liver function is usually part of therapy with tacrine.

Interactions Some cholinesterase inhibitors should be used with caution in persons with asthma or lung disease, as cholinesterase inhibitors may interact with theophylline, a drug commonly used to treat both conditions. 230

Resources BOOKS

Bird, T. D. “Memory loss and dementia.” In Harrison’s Principles of Internal Medicine, 15th edition, A. S. Franci, E. Daunwald, and K. J. Isrelbacher, eds. New York: McGraw Hill, 2001. Castleman, Michael, et. al. There’s Still a Person in There: The Complete Guide to Treating and Coping with Alzheimer’s. New York: Perigee Books, 2000. Fillit, Howard M. Drug Discovery and Development for Alzheimer’s Disease. New York: Springer, 2001. PERIODICALS

Cummings, J. L. “Cholinesterase inhibitors: a new class of psychotropic compounds.” American Journal of Psychiatry (January 2000): 4–14. Masterman, D. “Cholinesterase inhibitors in the treatment of Alzheimer’s disease and related dementias.” Clinical and Geriatric Medicine (February 2004): 59–68. OTHER

“Cholinesterase Inhibitors: Current Drug Treatments for Alzheimer Disease.” Alzheimer Society of Canada. (May 6, 2004). . National Institute of Neurological Disorders and Stroke. NINDS Alzheimer’s Disease Information Page. (May 6, 2004). . ORGANIZATIONS

Alzheimer Society of Canada. 20 Eglinton Avenue W., Suite 1200, Toronto, ON M4R 1K8, CANADA. (416) 488-8772 or (800) 616-8816; Fax: (416) 488-3778. [email protected]. . Alzheimer’s Association. 225 N. Michigan Avenue, Chicago, IL 60601. (312) 335-8700 or (800) 272-3900; Fax: (312) 335-1110. [email protected]. .

Brian Douglas Hoyle, PhD

❙ Chorea Definition

Chorea refers to brief, repetitive, jerky, or dancelike uncontrolled movements caused by muscle contractions that occur as symptoms of several different disorders. The English word “chorea” itself comes from the Greek word choreia, which means “dance.” The symptom takes its name from the rapid involuntary jerking or twitching movements of the patient’s face, limbs, and upper body.

Description A patient with chorea may appear restless, fidgety, or unable to sit still. The body movements are continually changing and may appear to move from one part of the

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Key Terms Athetosis A symptom of movement disorders that consists of slow, writhing, wavelike movements, usually in the hands or feet. It is also known as mobile spasm. It may occur together with chorea; the combined symptom is called choreoathetosis. Ballismus Involuntary violent flinging movements that may take the form of uncontrollable flailing. It is also called ballism. Ballismus that occurs with chorea is known as choreoballismus or choreoballism. Basal ganglia (singular, ganglion) Groups of nerve cell bodies located deep within the brain that govern movement as well as emotion and certain aspects of cognition (thinking). Chorea gravidarum Chorea occurring in the early months of pregnancy.

body to another. Jerking or twitching of the hands and feet may resemble piano playing or dancing. The patient may assume strange postures or make clumsy or wide-swinging leg movements when trying to walk. If the chest muscles are affected, the patient may have difficulty speaking normally, or make grunting or groaning noises. Facial expressions may be distorted by twitching of the lips, cheeks, eyebrows, or jaw. In severe cases, involuntary movements of the arms and legs may result in falling on the ground or throwing objects placed in the hand. Other symptoms that may occur together with chorea include athetosis, which refers to slow, sinuous, writhing movements of the hands and feet, and ballismus, which refers to violent flinging or flailing of the limbs. A patient with one of these symptoms in addition to chorea may be said to have choreoathetosis or choreoballismus. In some cases, only one side of the patient’s body is affected by the involuntary movements. This condition is known as hemichorea.

Causes and associated disorders The basic cause of choreic movements is overactivity of a neurotransmitter called dopamine in a set of structures deep within the brain known as the basal ganglia. The basal ganglia belong to a larger part of the nervous system that controls the muscles responsible for normal movement. Several different unrelated disorders and conditions may lead to imbalances of dopamine in the basal ganglia, including:

Dopamine A neurotransmitter that acts within certain parts of the brain to help regulate movement and emotion. Encephalitis Inflammation of the brain. Hemichorea Chorea that affects only one side of the body. Hyperthyroidism Abnormally high levels of thyroid hormone. About 2% of patients with this condition develop chorea. Hypocalcemia Abnormally low levels of calcium in the blood. Neurosyphilis Late-stage syphilis that affects the central nervous system. Neurotransmitter Any of a group of chemicals that transmit nerve impulses across the gap (synapse) between two nerve cells.

• Huntington’s chorea (HC), an incurable hereditary disorder caused by a mutation in a gene on the short arm of human chromosome 4. It is characterized by dementia and psychiatric disturbances as well as chorea. • Sydenham’s chorea, a treatable complication of rheumatic fever following a streptococcal throat infection. It occurs most often in children and adolescents. • Chorea gravidarum or chorea occurring in the first three months of pregnancy. It is most likely to affect women who had rheumatic fever or Sydenham’s chorea in childhood. • Senile chorea, which is gradual in onset, is not associated with other causes of chorea, does not cause personality changes, and develops in people over the age of 60. At one time, senile chorea was thought to be a late-onset form of HC, but is presently considered to be the result of a different genetic mutation. • Blockage or rupture of one of the arteries supplying the basal ganglia. • Metabolic disorders. About 2% of patients with abnormally high levels of thyroid hormone (hyperthyroidism) develop chorea. Abnormally low levels of calcium (hypocalcemia) may also produce chorea. • Infectious diseases that affect the central nervous system. Chorea may be a symptom of viral encephalitis or late-stage neurosyphilis. • Medications. Some drugs, most commonly those used to treat psychotic disorders or Parkinson’s disease, cause

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chorea as a side effect. Other drugs that sometimes cause chorea include anticonvulsants (antiepileptic drugs), lithium, amphetamines, and some antinausea medications.

Diagnosis A doctor diagnosing the cause of chorea is guided by such factors as the patient’s age and sex as well as medication history and family history. A patient with symptoms of Huntington’s chorea is typically an adult over 35, whereas Sydenham’s chorea most often occurs in children aged six to 14. Huntington’s chorea affects both sexes equally, whereas Sydenham’s chorea affects girls twice as often as boys. A patient with a family history of Huntington’s can be given a blood test to detect the presence of the gene that causes HC. A history of a recent throat infection or rheumatic fever suggests Sydenham’s chorea. Metabolic disorders can be detected by blood tests. Hemichorea or chorea accompanied by ballismus may indicate a vascular disorder affecting the basal ganglia, particularly when the chorea is sudden in onset. The doctor will order imaging studies, usually computed tomography (CT) scans or magnetic resonance imaging (MRI) if an arterial blockage or rupture is suspected. Neurosyphilis and encephalitis are diagnosed by testing a sample of the patient’s cerebrospinal fluid.

Treatment In general, chorea is not treated by itself unless the movements are so severe as to cause embarrassment or risk injury to the patient. Drugs that are given to treat chorea suppress the activity of dopamine in the basal ganglia but may also produce such undesirable side effects as muscular rigidity or drowsiness. These drugs cannot be given to women with chorea gravidarum because they may harm the fetus; pregnant patients may be given a mild benzodiazepine tranquilizer instead. Drugs given to treat patients with HD may help to control chorea, but cannot stop the progression of the disease.

Prognosis The prognosis of chorea depends on its cause. Huntington’s chorea is incurable, leading to the patient’s death 10–25 years after the first symptoms appear. Almost all children with Sydenham’s chorea, however, recover completely within one to six months. Chorea gravidarum usually resolves by itself when the baby is born or shortly afterward. Chorea caused by a vascular disorder may last for six to eight weeks after the blockage or rupture is treated. Chorea associated with metabolic disorders usually goes away when the chemical or hormonal imbalance is corrected. 232

Resources BOOKS

“Disorders of Movement.” The Merck Manual of Diagnosis and Therapy, edited by Mark H. Beers, MD, and Robert Berkow, MD. Whitehouse Station, NJ: Merck Research Laboratories, 2002. Martin, John H. Neuroanatomy: Text and Atlas, 3rd ed. New York: McGraw-Hill, 2003. “Movement Disorders: Choreas.” The Merck Manual of Geriatrics, edited by Mark H. Beers, MD, and Robert Berkow, MD. Whitehouse Station, NJ: Merck Research Laboratories, 2004. “Sydenham’s Chorea (Chorea Minor; Rheumatic Fever; St. Vitus’ Dance).” The Merck Manual of Diagnosis and Therapy, edited by Mark H. Beers, MD, and Robert Berkow, MD. Whitehouse Station, NJ: Merck Research Laboratories, 2002. PERIODICALS

Caviness, John M., MD. “Primary Care Guide to Myoclonus and Chorea.” Postgraduate Medicine 108 (October 2000): 163–172. Grimbergen, Y. A., and R. A. Roos. “Therapeutic Options for Huntington’s Disease.” Current Opinion in Investigational Drugs 4 (January 2003): 51–54. Jordan, L. C., and H. S. Singer. “Sydenham Chorea in Children.” Current Treatment Options in Neurology 5 (July 2003): 283–290. Karageyim, A. Y., B. Kars, R. Dansuk, et al. “Chorea Gravidarum: A Case Report.” Journal of Maternal-Fetal and Neonatal Medicine 12 (November 2002): 353–354. Sanger, T. D. “Pathophysiology of Pediatric Movement Disorders.” Journal of Child Neurology 18 (September 2003) (Supplement 1): S9–S24. Stemper, B., N. Thurauf, B. Neundorfer, and J. G. Heckmann. “Choreoathetosis Related to Lithium Intoxication.” European Journal of Neurology 10 (November 2003): 743–744. OTHER

Herrera, Maria Alejandra, MD, and Nestor Galvez-Jiminez, MD. “Chorea in Adults.” eMedicine, 1 February 2002 (April 27, 2004.) . National Institute of Neurological Disorders and Stroke (NINDS). NINDS Chorea Information Page. (April 27, 2004). . Ramachandran, Tarakad S., MD. “Chorea Gravidarum.” eMedicine, 9 June 2002 (April 27, 2004). . ORGANIZATIONS

American Geriatrics Society (AGS). Empire State Building, 350 Fifth Avenue, Suite 801, New York, NY 10118. (212) 308-1414; Fax: (212) 832-8646. info@american geriatrics.org. . Huntington’s Disease Society of America (HDSA). 158 West 29th Street, 7th Floor, New York, NY 10001-5300. (212)

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Rebecca Frey, PhD

Key Terms Demyelination Loss of the myelin sheath that surrounds and insulates the axons of nerve cells and is necessary for the proper conduction of neural impulses. Electromyography A test that detects electric activity in muscle that is used to determine nerve or muscle damage. Myelin The fatty covering that is wrapped around the outside of a nerve cell. Neuropathy A disorder of the nervous system or a nerve.

❙ Chronic inflammatory demyelinating polyneuropathy

Definition Chronic inflammatory demyelinating polyneuropathy (CIDP) is a disorder that affects the nerves outside of the brain and spinal cord (peripheral nerves). Specifically, the fatty covering, or sheath, that is wrapped around the outside of a nerve cell is damaged. The covering is called myelin, and the damage is called demyelination. The nerve damage becomes apparent as weakness in the legs and arms increases in severity with time.

Description The demyelination of peripheral nerves causes a weakness in the legs and arms that grows progressively more severe over time. The ability of the limbs to feel sensory impulses such as touch, pain, and temperature can also be impaired. Typically, the malady is first apparent as a tingling or numbness in the toes and the fingers. The symptoms can both spread and become more severe with time. The symptoms, treatment, and prognosis of CIDP is very similar to another nerve disease known as GuillainBarré syndrome. In fact, CIDP has been historically known as “chronic Guillain-Barré syndrome” (GuillainBarré syndrome is an acute malady whose symptoms appear and clear up more rapidly). Despite their similarities, however, CIDP and Guillain-Barré are two distinct conditions. CIDP is also known as chronic relapsing polyneuropathy.

Demographics CIDP can occur at any age. However, the malady is more common in young adults, and in men more than in women. The disorder is rare in the general population.

Causes and symptoms CIDP is an immune system disorder. Specifically, the immune system mistakenly recognizes the myelin sheath of the peripheral nerve cells as foreign. Damage to the sheath occurs when the immune system attempts to rid the body of the invader. There is no evidence to support a genetic basis for the disease, such as a family history of CIDP or other, similar disorders. CIDP cannot be inherited. As with Guillain-Barré syndrome, it is strongly suspected that CIDP is at least triggered by a recent viral infection. For example, critical immune cells can be damaged in viral infection such as occurs in acquired immunodeficiency syndrome (AIDS), leading to malfunction of the immune system. Whether viral or other microbial infections are the direct cause of CIDP is not clear. CIDP is different from Guillain-Barré syndrome in that the viral infection often does not occur within several months of the first appearance of the symptoms. In Guillain-Barré syndrome, a viral or bacterial infection typically immediately precedes the appearance of the symptoms. CIDP typically begins with a tingling or prickling sensation, or numbness in the fingers and toes. This can spread to the arms and legs (an ascending pattern of spread). Both sides of the body can be affected; this is described as a symmetrical pattern. Other symptoms that can develop over time include the loss of reflexes in some tendons (a condition referred to as areflexia), extreme tiredness, and muscle ache. In some people, these symptoms develop slowly, reach a peak over several weeks or months, and then resolve themselves over time. However, for the majority of people with CIDP, the symptoms do not improve without treatment, and the symptoms can persist for many months to years.

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242-1968 or (800) 345-HDSA; Fax: (212) 239-3430. [email protected]. . National Institute of Neurological Disorders and Stroke (NINDS). 9000 Rockville Pike, Bethesda, MD 20892. (301) 496-5751 or (800) 352-9424. . Worldwide Education and Awareness for Movement Disorders (WE MOVE). 204 West 84th Street, New York, NY 10024. (212) 875-8389 or (800) 437-MOV2. [email protected]. .

Chronic inflammatory demyelinating polyneuropathy

Diagnosis An important part of the diagnosis of CIDP is the detection of muscle weakness by a neurological examination. One relevant neurological test is nerve conduction velocity. In this test, a patch that is attached to the skin’s surface over the target muscle is stimulated. A very mild electrical current stimulates the nerves in the muscle. A measurement called the nerve conduction velocity is then calculated as the time it takes for the impulses to travel the known distance between electrodes. In demyelinating diseases such as CIDP, the nerves are not capable of transmitting electrical impulses as speedily as normal, myelinated nerves. Thus, the damaged nerves will display a greater conduction velocity than that displayed by an unaffected person. Another test called electromyography (EMG) is used to measure muscle response to electrical stimulation. In EMG, an electrode contained within a needle is pushed through the skin into the muscle; several electrodes may need to be inserted throughout a muscle to accurately measure the muscle’s behavior. Stimulation of a muscle causes a visual or audio pattern. The pattern of wavelengths carries information about the muscle’s response. The characteristic pattern of wavelengths produced by a healthy muscle, which is called the action potential, can be compared to a muscle in someone suspected of having CIDP. For a nerve-damaged muscle, the action potential’s wavelengths are smaller in height and less numerous than displayed by a normal muscle. An electrocardiogram can be used to record the electrical activity of the heart when paralysis of the heart muscle is suspected. Nerve damage will alter the normal pattern of the heartbeat. Finally, an examination of the cerebrospinal fluid by a lumbar puncture (also known as a spinal tap) may detect a higher than normal level of protein in the absence of an increase in the number of white blood cells (WBCs). An increase in WBCs occurs when there is a microbial infection.

Another procedure that produces similar results involves the administration of intravenous immunoglobulin (IVIG). IVIG is a general all-purpose treatment for immune system-related neuropathies. As with plasmapheresis, immunoglobulin may help reduce the amount of anti-myelin antibodies, and so suppress the immune response. As well, IVIG contains healthy antibodies from the donated blood. These antibodies can help neutralize the defective antibodies that are causing the demyelination. When more standard approaches fail, alternative forms of immunosuppressive therapies are sometimes considered, including the drugs azathioprine, cyclophosphamide, and cyclosporine. Physical therapy is helpful. Caregivers can move a patient’s arms and legs to help improve the strength and flexibility of the muscles, and minimize the shrinkage of muscles and tendons that are not being actively used.

Recovery and rehabilitation Recovery from CIDP varies from person to person. Some people recover completely without a great deal of medical intervention, while others may relapse again and again. Because some people can display permanent muscle weakness or numbness, physical therapy can be a useful part of a rehabilitation regimen.

Clinical trials

Treatment team CIDP treatment typically involves neurologists, immunologists, and physical therapists. Support groups are a useful adjunct to treatment.

Treatment The treatments for CIDP and Guillain-Barré syndrome are similar. The use of corticosteroids such as prednisone, which lessen the response of the immune system, can reduce the amount of demyelination that occurs. Corticosteroids can be prescribed alone or in combination with other immunosupressant drugs. 234

The medical procedure known as plasmapheresis, or plasma exchange, can be another useful treatment. In plasmapheresis, the liquid portion of the blood that is known as plasma is removed from the body. The red blood cells are retrieved from the plasma and added back to the body with antibody-free plasma or intravenous fluid. Although plasmapheresis can lessen the symptoms of CIDP, it is not known exactly why plasmapheresis works. Because the blood plasma withdrawn from the body of a CIDP patient can contain antibodies to the nerve myelin sheath, the subsequent removal of these antibodies may lessen the effects of the body’s immune attack on the nerve cells.

The National Institutes of Health (NIH) sponsored four clinical trials for the study and treatment of CIDP, all completed by 2001. The National Institute of Neurological Disorders and Stroke supports continued broad research for demyelinating diseases, although no further clinical trials are ongoing as of March 2004.

Prognosis A patient’s prognosis can range from complete recovery to a pattern of a periodic reappearance of the symptoms and residual muscle weakness or numbness.

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The potential exists that IVIG will increase the risk of kidney damage in older or diabetic patients. Enoxaparin, a drug that can be prescribed to reduce the risk of blood clotting in patients with high blood pressure, can make a patient more prone to bleeding. This risk can be greater when enoxaparin is given at the same time as aspirin or anti-inflammatory drugs. The use of corticosteroids can restrict the efficiency of the immune system, which can increase the risk that other microorganisms will establish a secondary, or opportunistic, infection. Medical staff regularly monitor people receiving these treatments for signs of complication. Resources BOOKS PERIODICALS

Comi, G., A. Quattrini, R. Fazio, and L. Roveri. “Immunoglobulins in Chronic Inflammatory Demyelinating Polyneuropathy.” Neurological Science (October 2003): S246–S250. Fee, D. B., and J. O. Flemming. “Resolution of Chronic Inflammatory Demyelinating Polyneuropathy-associated Central Nervous System Lesions after Treatment with Intravenous Immunoglobulin.” Journal of the Peripheral Nervous System (September 2003): 155–158. Katz, J. S., and D. S. Saperstein. “Chronic Inflammatory Demyelinating Polyneuropathy.” Current Treatment Options in Neurology (September 2003): 357–364. OTHER

NINDS Chronic Inflammatory Demyelinating Polyneuropathy (CIDP) Information Page. National Institute of Neurological Disorders and Stroke. December 22, 2003 (March 30, 2004). . ORGANIZATIONS

American Autoimmune Related Diseases Association. 22100 Gratiot Avenue, Eastpointe, MI 48201-2227. (586) 7763900 or (800) 598-4668; Fax: (586) 776-3903. [email protected]. . Guillain-Barre Syndrome Foundation International. P.O. Box 262, Wynnewood, PA 19096. (610) 667-0131; Fax: (610) 667-7036. [email protected]. . National Organization for Rare Disorders. P.O. Box 1968, Danbury, CT 06813-1968. (203) 744-0100. [email protected]. . Neuropathy Association. 60 East 42nd Street, New York, NY 10165-0999. (212) 692-0662 or (800) 247-6968; Fax: (212) 696-0668. [email protected]. .

Brian Douglas Hoyle, PhD

Circle of Willis see Cerebral circulation

❙ Clinical trials Definition

A clinical trial is a carefully designed research study that is carried out with human volunteers. The trial is designed to answer specific questions concerning the effectiveness of a drug, treatment, or diagnostic method, or to improve patients’ quality of life.

Description Qualification for a clinical trial involves the selection of various desirable criteria (inclusion criteria), as well as criteria by which volunteers are rejected (exclusion criteria). Typical criteria include age, gender, the type and severity of the disease, prior treatment, and other medical conditions. Depending on the clinical trial, the volunteers that are recruited could be healthy or ill with the disease under study. There are a number of different types of clinical trials that utilize differing types of study plans (protocols). A treatment trial evaluates a new treatment, new drug combinations, new surgical strategies, or innovative radiation therapy. A prevention trial seeks to find better ways to prevent disease from occurring or prevent disease from returning. Medicines, vaccines, vitamins, and lifestyle changes can all be candidates for a prevention trial. A diagnostic trial is designed to find better means of diagnosis for a particular disease or medical condition. A screening trial is designed to determine the best way to detect a particular disease or medical condition. Finally, a quality of life trial (supportive care trial) seeks to improve the comfort and daily life of people with a chronic illness. Clinical trials, particularly treatment and prevention trials, often have several components, or phases. The following phases (I-IV) relate to the scope of the trial: • Phase I trial evaluates the new drug or treatment in a small group of people (less than 100). Humans do not necessarily need to participate in such a trial. Experiments in the lab using microbiological cultures or tissue cells may suffice. The trial’s purpose is to provide early indications of a drug or treatment’s safety, safe dosage range, and reveal any side effects. • Phase II trial follows a phase I trial. A promising drug or treatment is tested on a larger group of people (100–300) to better determine the effectiveness and to monitor safety more critically. Use of a larger population can help reveal side effects that could be hidden by the use of only a few volunteers. • Phase III trial evaluates a drug or treatment that has proven effective in the phase I and II trials and is tested

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Special concerns

Congenital myasthenia

Key Terms Double blind study A study or clinical trial designed to minimize any bias, in that neither participant or study director knows who is assigned to the control group and who is assigned to the test group until the end of the study. Exclusion criteria A predetermined set of factors that make a potential participant not eligible for inclusion in a clinical trial or study. Inclusion criteria A predetermined set of factors that make a potential participant eligible for inclusion in a clinical trial or study. Placebo A drug containing no active ingredients, such as a sugar pill, that may be used in clinical trials to compare the effects of a given treatment against no treatment.

on a large population (1,000–3,000) to confirm its effectiveness, reveal any rarer side effects, and gather information that will allow the drug or treatment to be safely marketed. • Phase IV trial occurs after a product has been released in the marketplace. Monitoring of a drug or treatment in very large numbers of people provides further information on benefits and risks. A typical clinical trial involves medical doctors and nurses, although social workers and other health care workers may also contribute. The members of the clinical team monitor the health of each volunteer at the outset and during the trial, give instructions, and often provide follow-up after the trial is completed. For a clinical trial volunteer, this means more visits to the health care facility than would normally occur, although compensation such as transportation expense is sometimes provided. A critical part of a clinical trial is obtaining the consent of volunteers for their participation. It is mandatory that a trial’s risks (i.e., side effects, little or no effect of treatment) and benefits (i.e., more proactive role in health care, access to new therapies, advance medical care) be clearly explained to participants. Once this is done, volunteers provide their informed consent by signing a document. This document is not legally binding, so volunteers are not obligated to complete the trial. An ethical clinical trial will never reveal the identities of the volunteers. In addition to the drug being studied, clinical trials of new drugs will typically use a pill, liquid, or powder that looks the same as the active compound, but that has no medicinal value. This inactive compound, known as a 236

placebo, is usually given to the control group of volunteers, who are compared to the test group that receives the active drug. Usually the volunteers do not know whether they receive a placebo or the active drug. A clinical trial can be designed so that the researchers are also unaware of which people receive the active drug. When volunteers and researchers are both unaware, the trial is described as being double blind. Volunteers are often assigned to the control or test groups at random. This action is designed to minimize any bias due to age, gender, race, or other factors. Resources OTHER

“An Introduction to Clinical Trials.” ClinicalTrials.gov. January 21, 2004 (March 30, 2004). . ORGANIZATIONS

National Institutes of Health, Clinical Center. 6100 Executive Blvd., Suite 3C01MSC 7511, Bethesda, MD 20892-7511. (301) 496-2563 or (800) 411-1222; Fax: (301) 402-2984. [email protected]. .

Brian Douglas Hoyle, PhD

Cluster headache see Headache Complex regional pain syndrome see Reflex sympathetic dystrophy Congenital facial diplegia see Moebius syndrome Congenital vascular cavernous malformation see Cerebral cavernous malformation

❙ Congenital myasthenia Definition

Congenital myasthenia is an inherited condition present at birth that interferes with nerve messages to the muscles. Although some symptoms are similar (muscle weakness worsened by use), congenital myasthenia differs from myasthenia gravis, which usually presents in adulthood and is almost always due to an autoimmune disorder rather than an inherited genetic defect.

Description Most cases of congenital myasthenia are noticeable at or shortly after birth. In rare cases, symptoms don’t present themselves until some time later in childhood or in early adult life.

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In congenital myasthenia, one of three problems occurs with this system: • Too little ACh is produced, or its release from the nerve cell is impaired • The enzyme that should degrade ACh is faulty, resulting in prolonged stimulation of the muscle by excess ACh and ultimately in muscle damage • The area of the muscle that should be stimulated by the presence of ACh (called the endplate receptor) is defective, and therefore the muscle can not be sufficiently stimulated

with repeated stimulation, congenital myasthenia is suspected. Testing the blood for the presence of specific antibodies can help distinguish between myasthenia gravis and congenital myasthenia. Very specific microelectrode testing of the muscle endplate receptors can help define whether faulty receptors are responsible for the impairment. Genetic testing and muscle biopsy examination are being researched, but are not currently used for routine diagnosis.

Treatment team Children with congenital myasthenia will usually be treated by a team consisting of a pediatric neurologist, as well as a physical therapist, occupational therapist, and speech and language therapist. If respiratory problems ensue, a pulmonologist and respiratory therapist may need to be consulted.

Demographics Figures regarding the frequency of congenital myasthenia are not available, but it is considered to be a very rare condition.

Causes and symptoms Most cases of congenital myasthenia are inherited in a recessive fashion, meaning that a baby has to receive a defective gene from each parent to actually manifest the condition. Babies with congenital myasthenia are often described as “floppy,” with weak muscle tone, droopy eyelids, excessive fatigue, compromised eye movements, facial weakness, feeding problems and delayed developmental milestones (such as holding up head, sitting, crawling). In more severe conditions, the muscles that aid breathing are affected, resulting in respiratory difficulties. The baseline degree of weakness is exacerbated by any activity, including feeding, crying, or moving. Episodes of more severe symptoms may be precipitated by illness, emotional upset, or fever. Some cases of congenital myasthenia progress over time, so that initially mild symptoms can become more severe as the individual ages.

Treatment There are no treatments available to cure congenital myasthenia. A number of medications may improve symptoms in children with congenital myasthenia. The specific medication that will be most helpful depends on whether the impairment is due to decreased ACh production and release, impaired enzyme degradation of ACh, or faulty ACh receptors in the muscle endplates. Some of the types of medications available include: • Anticholinesterase medications: Inhibit the degradation of ACh, allowing more to be available to stimulate muscles. • 3,4, diaminopyridine: Increases the release of ACh from the nerve cells. • Qunidine or fluoxetine: Prevents overstimulation of ACh receptors on muscle endplates, thus preventing muscles from damage secondary to prolonged stimulation.

Prognosis The severity of symptoms, responsiveness to medication, and ultimate prognosis varies widely among congenital myasthenia patients. Resources

Diagnosis The diagnosis of congenital myasthenia will usually be suspected when a careful physical examination reveals muscle weakness that is worsened by use of a particular muscle. Certainly, a family history of congenital myasthenia heightens such a suspicion. A test called electromyography measures muscle activity after stimulation. When muscle activity decreases

BOOKS

“Nutritional Disorders of the Neuromuscular Transmission and of Motor Neurons.” In Nelson Textbook of Pediatrics, edited by Richard E. Behrman, et al. Philadelphia: W. B. Saunders Company, 2004. Rose, Michael, and Robert C. Griggs. “Congenital Myasthenias.” In Textbook of Clinical Neurology, edited by Christopher G. Goetz. Philadelphia: W. B. Saunders Company, 2003.

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Normal muscle function requires a chemical messenger called acetylcholine (ACh) to travel from the nerve cell to a receptor on the muscle endplate, in order to stimulate muscle contraction and movement. After the ACh has initiated muscle contraction, it is degraded by an enzyme.

Congenital myopathies

ORGANIZATIONS

Key Terms

Muscular Dystrophy Association. 3300 East Sunrise Drive, Tucson, AZ 85718. (800) 572-1717. [email protected]. .

Congenital Present at birth.

Rosalyn Carson-DeWitt, MD

Gene A building block of inheritance, which contains the instructions for the production of a particular protein, and is made up of a molecular sequence found on a section of DNA. Each gene is found on a precise location on a chromosome.

❙ Congenital myopathies Definition

Myopathies are diseases that cause weakness and hypotonia (poor tone) in the muscles that control voluntary movements. Congenital myopathies are a group of myopathies, usually present from birth, that display structural changes in the skeletal muscles. The list of diseases defined as congenital myopathies varies. Three inherited conditions in particular are definitively known as congenital myopathies: central core disease, nemaline myopathy, and centronuclear (myotubular) myopathy. These myopathies lead to generalized muscle weakness, decreased muscle tone, weak muscle reflexes, poor muscle bulk, and often a characteristic facial and bodily appearance.

Description Central core disease First described in 1956, central core disease (CCD) is named for the abnormalities found in the muscle biopsies of affected people. The central parts, or cores, of certain muscle cells lack structures called mitochondria, the energy-producing parts of the cells. CCD is a variable disorder with onset in early infancy to childhood. Hip displacement is not uncommon. Some children with CCD show mildly delayed motor milestones and appear only slightly uncoordinated. Others have more significant delays, though they eventually walk and move about with some limitation. Some children use braces for walking, and a few use wheelchairs. Nemaline myopathy Also known as rod myopathy or rod body disease, nemaline myopathy (NM) was first described in two separate reports in 1963. NM is named for the thread-like structures known as nemaline bodies that are visible on muscle biopsy. The term “nemaline” comes from the Greek word nema meaning “thread.” The main features of NM are muscle weakness, loss of muscle tone, and absent or weak deep tendon reflexes (for example, knee and ankle jerks). Based on the age of onset and severity of symptoms, NM has been classified into six forms: neonatal (severe congenital), Amish nemaline myopathy (a congenital form), 238

Fetal Refers to the fetus. In humans, the fetal period extends from the end of the eighth week of pregnancy to birth.

Nerve conduction The speed and strength of a signal being transmitted by nerve cells. Testing these factors can reveal the nature of nerve injury, such as damage to nerve cells or to the protective myelin sheath. Serum The fluid part of the blood that remains after blood cells, platelets, and fibrogen have been removed. Also called blood serum.

intermediate congenital form, typical congenital form, childhood-onset form, and adult-onset form. Most cases (over 80%) are one of the congenital forms. All six forms of NM are unified by the presence of nemaline rods, abnormal structures that are found in the sarcoplasm of the muscles. Centronuclear (myotubular) myopathy Centronucler myopathy, also known as myotubular myopathy (MTM), is an extremely variable condition characterized by a poor muscle tone and weakness. The centronuclear myopathies are called “myotubular myopathies” due to the presence of myotubes, immature muscle cells found in affected individuals. Myotubes have nuclei (structures that contain the chromosomes) that are central rather than peripheral (at the edge). Mature muscle cells have peripheral nuclei. Although MTM can lead to death in infancy, it can be a mildly progressive condition that begins as late as early adulthood. There are X-linked, autosomal dominant and autosomal recessive forms of the disorder. The X-linked form, also known as X-linked myotubular myopathy or XLMTM, is thought to be the most common form of the condition and typically is the most severe form of MTM.

Demographics Although central core disease is thought to be rare, the incidence of this congenital myopathy remains unknown. Both males and females are affected. Due to the range of severity observed in CCD, it is possible that there

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Causes and symptoms Causes CENTRAL CORE DISEASE Central core disease is inherited in an dominant manner, due to a mutation in one copy of the RYR1 (ryanodine receptor) gene on the long arm of chromosome 19. Researchers think that mutations in this receptor affect the way calcium flows out of the sarcoplasmic reticulum, a functional unit in the muscle. Mutations in the RYR1 gene are also known to cause malignant hyperthermia (MH), a genetic predisposition that makes an individual prone to serious reactions to certain general anesthetics. In fact, MH is a feature of CCD. An individual with CCD has a 50% chance of passing the disorder on to each child. There are also occurrences of sporadic inheritance, which means that a gene alters spontaneously to cause the disorder in a person with no family history of the disease. NEMALINE ROD MYOPATHY Nemaline myopathy is caused by alterations in genes that affect filament proteins. When the filament proteins aren’t working, muscles can’t contract and there is a subsequent loss of tone and strength. Nemaline myopathy can be inherited as an autosomal dominant or an autosomal recessive condition. Autosomal dominant inheritance implies that the affected person has one altered or non-functioning copy and one normal copy of a particular NM gene. The changed gene may occur for the first time in that individual (de novo) or may be inherited from a parent (familial). When NM occurs as an autosomal recessive condition, the affected individual has two altered or non-functioning NM genes, one from each parent. As of March 2004, there were five genes known to cause NM abbreviated as ACT1, NEB, TNNT1, TMP2, and TMP3; each gene codes for protein components of thin filament, a type of muscle fiber. MYOTUBULAR MYOPATHY The MTM1 gene on the long arm of the X chromosome encodes myotubularin, a protein thought to promote normal muscle development. As of 2004, the precise mechanisms by which MTM1 mutations cause XLMTM were unresolved. X-linked MTM primarily affects males because they have only one X chromosome and therefore lack a second, normal copy of the gene responsible for the condition. Female carriers of the X-linked MTM have one X chromosome with a normal MTM1 gene and one X chromosome with a nonworking MTM1 gene. As of March 2004, researchers were

working to identify the gene or genes responsible for the autosomal recessive form of centronuclear myopathy. One gene, the myogenic factor-6 gene (MYF6) has been shown to cause some cases of the autosomal dominant form. It is possible that other genes will be discovered in the future. Symptoms CENTRAL CORE DISEASE Central core disease is characterized by a mild, non-progressive muscle weakness. Signs of central core disease usually appear in infancy or early childhood and may present even earlier. There may be decreased fetal movements and breech (feet first) presentation in utero. The main features of CCD are poor muscle tone (hypotonia), muscle weakness, and skeletal problems including congenital hip dislocation, scoliosis (curvature of the spine), pes cavus (high-arched feet), and clubbed feet. Children with CCD experience delays in reaching motor milestones and tend to sit and walk much later than those without the disorder. A child with the disease usually cannot run easily, and may find that jumping and other physical activities are often impossible. Although central core disease may be disabling, it usually does not affect intelligence or life expectancy. People who have central core disease are sometimes vulnerable to malignant hyperthermia (MH), a condition triggered by anesthesia during surgery. MH causes a rapid, and sometimes fatal, rise in body temperature, producing muscle stiffness. NEMALINE MYOPATHY There is variability in age of onset, presence of symptoms, and severity of symptoms in nemaline myopathy. Most commonly, NM presents in infancy or early childhood with weakness and poor muscle tone. In some cases there may have been pregnancy complications such as polyhydramnios (excess amniotic fluid) and decreased fetal movements. Affected children with NM tend to have delays in motor milestones such as rolling over, sitting and walking. Muscle weakness commonly occurs in the face, neck and upper limbs. Over time, a characteristic myopathic face (a long face that lacks expression) develops. Skeletal problems including chest deformities, scoliosis, and foot deformities may develop. In the most severe cases of NM, feeding difficulties and potentially fatal respiratory problems may also occur. In those who survive the first two years of life, muscle weakness tends to progress slowly or not at all. CENTRONUCLEAR MYOPATHY Typically the X-linked form of MTM (XLMTM) is the most severe of the three forms (X-linked, autosomal recessive, and autosomal dominant). XLMTM usually presents as a newborn male with poor muscle tone and respiratory distress. The pregnancy may have been complicated by polyhydramnios and decreased fetal movements. Of those who survive the newborn period, many will at least partially depend on a ventilator for breathing. Because of the risk of aspiration,

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are undiagnosed cases within CCD families and within the general population. The X-linked form of centronuclear myopathy affects approximately 1/50,000 newborn males. The autosomal recessive and autosomal dominant forms are apparently less common; however, the frequency of these forms remains unknown. Nemaline myopathy occurs in about 1/50,000 live births.

Congenital myopathies

many will also have a gastrostomy tube (G-tube). Boys with XLMTM can experience significant delays in achieving motor milestones and may not ever walk independently. They tend to be tall with a characteristic facial appearance (long, narrow face with a highly arched roof of the mouth and crowded teeth). Intelligence is generally not affected. Medical complications that may develop include: scoliosis, eye problems (eye muscle paralysis and droopy eyelids), and dental malocclusion (severe crowding). In Xlinked MTM, other problems including undescended testicles, spherocytosis, peliosis, elevated liver enzymes, and gallstones may occur. The autosomal recessive and autosomal dominant forms of MTM tend to have a milder course than the Xlinked form. The autosomal recessive form can present in infancy, childhood, or early adulthood. Common features include generalized muscle weakness with or without facial weakness and ophthalmoplegia (paralysis of the eye muscles). Although feeding and breathing problems can occur, affected individuals usually survive infancy. Onset of the autosomal dominant form ranges from late childhood through early adulthood. It tends to be the mildest of the three forms of MTM. Unlike the X-linked form of the condition, problems with other organs (such as the liver, kidneys, and gall bladder) haven’t been reported with the autosomal recessive and autosomal dominant forms of MTM.

Diagnosis Diagnosis of a congenital myopathy generally includes evaluation of the patient’s personal and family history, physical and neurological examinations that test reflexes and strength, and specialized tests. Since there is overlap between the symptoms of a congenital myopathy and other neuromuscular disorders, a number of tests may be performed to help narrow down the diagnosis. Serum CK (creatinine kinase) analysis, EMG (electromyelogram), nerve conduction studies, and muscle ultrasound tend to be of limited value in making this diagnosis. The definitive diagnosis of a congenital myopathy usually relies upon genetic testing and/or muscle biopsy. Also, muscle biopsy can be used to determine a patient’s susceptibility to malignant hyperthermia. Central core disease The muscle biopsy from a person with CCD typically displays a metabolically inactive “core” or central region that appears blank when stained (tested) for certain metabolic enzymes (proteins) that should be there. These central regions also lack mitochondria, the energy producing “factories” of the cells. Genetic testing for RYR1 mutations is available on a research basis. The same genetic test may be used to determine the presence of the gene change 240

in family members who may have or be at-risk for the disease. For families in which a RYR1 mutation has been found, prenatal diagnosis may be possible using the DNA of fetal cells obtained from chorionic villus sampling (CVS) or amniocentesis. Nemaline myopathy The clinical diagnosis of NM is suspected in an infant under age one with muscle weakness and hypotonia (decreased muscle tone). Definitive diagnosis of nemaline myopathy is made by demonstration of nemaline bodies, rod-shaped structures characteristic of this disease, using a specific stain known as “Gomori trichrome” on a muscle biopsy sample. Muscle biopsy may also show predominance of structures known as type I fibers. As of 2004, genetic testing was available on a clinical basis for one gene, the ACTA1 gene located on the long arm of chromosome 1. About 15% of NM cases are due to mutations in this gene. Prenatal diagnosis is possible for families with known ACTA1 mutations. The DNA of a fetus can be tested using cells obtained from chorionic villus sampling (CVS) or amniocentesis. Centronuclear (myotubular) myopathy Diagnosis of X-linked MTM is usually made on muscle biopsy. Findings include: centrally located nuclei in muscle fibers that look like myotubules, absence of structures known as myofibrils, and possibly, persistence of certain proteins usually seen in fetal muscle cells. If timing is not an issue, genetic testing may be undertaken. Gene testing detects a mutation (disease-causing gene change) in up to 97-98% of people with the X-linked form. Though genetic testing is available, it tends to be time intensive and used to confirm a diagnosis, to screen potential carriers, or for prenatal testing.

Treatment team Management of a congenital myopathy requires a multidisciplinary approach. In addition to the patient’s primary health care professionals, medical professionals involved in the care of patients with may include specialists in neurology, neonatology, pulmonology, gastroenterology, orthopedics, ophthalmology, and orthodontistry. Additional specialists in physical therapy, speech therapy and occupational therapy may be needed. Patients with one of the congenital myopathies may receive comprehensive services through a muscular dystrophy association (MDA) clinic and/or a Shriner’s Hospital for Children. Genetic evaluation and counseling may be helpful to the patient and family, especially at the time of diagnosis. Psychological counseling and support groups may also assist families in coping with this condition.

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As of 2004, there is no cure for the congenital myopathies. The purpose of treatment, which is largely supportive, is to help patients optimize function and to manage any medical complications associated with the disorder. Treatment measures for the congenital myopathies greatly depend on the severity of the individual’s symptoms, and especially upon the degree of muscle weakness and presence of skeletal deformities. Treatment mainly consists of respiratory and feeding support, and orthopedic intervention. Ophthalmologic and dental care is also important to help manage problems that may arise such as dry eyes and dental crowding. In the case of X-linked MTM, management of associated complications including undescended testicles, spherocytosis, peliosis, elevated liver enzymes, and gallstones is also recommended. Affected infants, especially those with X-linked myotubular myopathy or nemaline myopathy, usually require a feeding tube (a gastrostomy or G-tube) for nutrition and mechanical ventilation through a tracheostomy to help with breathing. Other means of ventilation such as BiPAP (bilevel positive airway pressure) may be used. Even children and adults who don’t require help with daytime breathing may require respiratory support at night, since respiratory failure during sleep can occur. Braces or surgery may be necessary to treat scoliosis, dislocated hips, and foot deformities. Since individuals with central core disease can develop malignant hyperthermia during surgery, they should consult a neurologist or anesthesiologist prior to these or other surgeries.

Recovery and rehabilitation Given the rarity of the congenital myopathies, the potential for rehabilitation in these disorders is largely unknown. Speech, physical, and occupational therapies may be recommended. Though intellect is typically normal, educational support through early intervention services and/or through an individualized education plan (IEP) may also be appropriate for some children. In severe cases, consideration may be given to placement in a residential care facility that can provide 24-hour care and support services. The goal of rehabilitation for the congenital myopathies is to maintain or improve the patient’s existing functions. Physical therapy may be recommended to improve mobility and muscle strength. For example, people with central core disease can benefit from exercise, under the direction of a physician. Speech therapy can help a person with a congenital myopathy to learn speech and/or ways to communicate. For example, a boy with X-linked myotubular myopathy who has a tracheostomy may need help learning how to communicate with sign language

and, later, with writing boards. Occupational therapy can teach patients to use adaptive techniques and devices that may help compensate for muscle weakness. For example, someone with a severe form of nemaline myopathy may benefit from a walker, wheelchair or other device in order to get around.

Clinical trials As of March 2004, one clinical trial was recruiting patients with congenital myopathy. A study designed to learn more about the natural history of inherited neurological disorders and the role of heredity in their development will be conducted in the United States. Updated information on this trial can be found at or by contacting the patient recruitment and public liaison office of the National Institute of Neurological Disorders and Stroke (NINDS) at 1-800-411-1222 or .

Prognosis The outlook for children with central core disease is generally positive. Although they begin life with some developmental delays, many improve as they get older and stay active throughout their lives. The outcome for patients with nemaline rod myopathy is quite variable. Depending upon disease severity, affected individuals can have normal life span, despite progressive muscle weakness, or they can die in infancy due to respiratory problems. Severe neonatal respiratory disease and the presence of arthrogryposis (limited joint movement due to contracted muscles and tendons) generally predict a poor outcome with death by age one. The prognosis for myotubular myopathy varies according to the presence and severity of respiratory disease and scoliosis. X-linked myotubular myopathy was once described as fatal in the first few months of life. Yet, it is now known that support of feeding (G-tube) and ventilation (tracheostomy) can significantly improve life expectancy and quality of life.

Special concerns Malignant hyperthermia, a problem seen in some individuals with central core disease is a severe and potentially life-threatening complication of anesthesia. People with central core disease or a family history of the disease should consult their doctors about anesthesia risks. Also, wearing a medical alert bracelet may be advised. Individuals with even mild cases of myotubular myopathy can experience potentially serious breathing problems such as hypoxia (lack of oxygen) during sleep. It is crucial that even patients with minimal disease severity be monitored for respiratory problems as they may require help with breathing at night.

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Treatment

Corpus callosotomy

Resources BOOKS

Wallgren-Pettersson, Carina A., and Angus Clarke. “Congenital Myopathies.” In Principles and Practice of Medical Genetics. 4th ed., edited by David Rimoin, MD, PhD, Michael Connor, Reed E. Pyeritz, MD, PhD, and Bruce Korf, MD, PhD, 4th ed. New York: Churchill Livingstone, 2002. “Muscle Diseases.” In Textbook of Primary Care Medicine. 3rd ed. edited by John Noble, MD, Harry Greene, II, MD, Wendy Levinson, MD, Geoffrey A. Modest, MD, Cynthia D. Mulrow, MD, Joseph Scherger, MD; and Mark J. Young, MD. St. Louis, MO: Mosby, 2000.

Conjugate eye movements see Visual disturbances; Traumatic brain injury

❙ Corpus callosotomy Definition

Corpus callosotomy is a treatment for epilepsy, in which a group of fibers connecting the two sides of the brain, called the corpus callosum, is cut.

PERIODICALS

Bruno, C., and C. Minetti. “Congenital myopathies.” Current Neurol Neurosci Rep 4 (January 2004): 68–73. Jungbluth, H., C. A. Sewry, and F. Muntoni. “What’s new in neuromuscular disorders? The congenital myopathies.” European Journal of Paediatric Neurology 7 (2003): 23–30. Prasad, A. N., and C. Prasad. “The floppy infant: contribution of genetic and metabolic disorders.” Brain Dev 25 (October 2003): 457–76. Quinllivan, R. M., C. R. Muller, M. Davis, N. G. Laing, G. A. Evans, J. Dwyer, J. Dove, A. P. Roberts, and C. A. Sewry. “Central core disease: clinical, pathological, and genetic features.” Archives of Disease in Childhood 88 (December 2003): 68–1051–1055. Sanoudou, D., and A. Beggs. “Clinical and genetic heterogeneity in nemaline myopathy—a disease of skeletal muscle thin filaments.” Trends in Molecular Medicine 7 (August 2001): 362–368. WEBSITES

Muscular Dystrophy Association (MDA). Central Core Disease Page. . Muscular Dystrophy Association (MDA). Nemaline Myopathy Page. . Muscular Dystrophy Association (MDA). Myotubular Myopathy Page. . National Institute of Neurological Disorders and Stroke (NINDS). Congenital Myopathies Information Page. . ORGANIZATIONS

Muscular Dystrophy Association, 3300 East Sunrise Drive, Tucson, AZ 85718. (520) 529-2000 or (800) 572-1717; Fax: (520) 529-5300. [email protected]. . Myotubular Myopathy Resource Group. 2602 Quaker Drive, Texas City, TX 77590. (409) 945-8569. [email protected]. . Nemaline Myopathy Foundation. P. O. Box 5937, Round Rock, TX 78683-5937. .

Dawn J. Cardeiro, MS, CGC 242

Purpose Corpus callosotomy is used to treat epilepsy that is unresponsive to drug treatments. A person with epilepsy may be considered good candidate for one type of epilepsy surgery or another if he or she has seizures that are not adequately controlled by drug therapy, and has tried at least two (perhaps more, depending on the treatment center’s guidelines) different anti-epileptic drugs. The seizures of epilepsy are due to unregulated spreading of electrical activity from one part of the brain to other parts. In many people with epilepsy, this activity begins from a well-defined focal point, which can be identified by electrical testing. Surgical treatment of focal-origin seizures involves removal of the brain region containing the focal point, usually in a procedure called temporal lobectomy. In other people, no focal point is found, or there may be too many to remove individually. These patients are most likely to receive corpus callosotomy. The purpose of a corpus callosotomy is to prevent spreading of seizure activity from one half of the brain to the other. The brain is divided into two halves, or hemispheres, that are connected by a thick bundle of nerve fibers, the corpus callosum. When these fibers are cut, a seizure that begins in one hemisphere is less likely to spread to the other. This can reduce the frequency of seizures significantly. The initial surgery may cut the forward two-thirds of the corpus callosum, leaving the rest intact. If this does not provide sufficient seizure control, the remaining portion may be cut. Corpus callosotomy is most often performed for children with “drop attacks,” or atonic seizures, in which a sudden loss of muscle tone causes the child to fall to the floor. It is also performed in people with uncontrolled generalized tonic-clonic, or grand mal, seizures, or with massive jerking movements. Of the 20,000 to 70,000 people in the United States considered candidates for any type of epilepsy surgery, approximately 5,000 receive surgery per year. Between 1985 and 1990, more than 800 corpus

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Description During corpus callosotomy, the patient is under general anesthesia, lying on the back. The head is fixed in place with blunt pins attached to a rigid structure. The head is shaved either before or during the procedure. Incisions are made in the top of the skull to remove a flap of bone, exposing the brain. The outer covering is cut, and the two hemispheres are pulled slightly apart to expose the corpus callosum. The fibers of the corpus callosum are cut, taking care to avoid nearby arteries and ventricles (fluid-filled cavities in the brain). Once the cut is made and any bleeding is controlled, the brain covering, bone, and scalp are closed and stitched.

Preparation The candidate for any type of epilepsy surgery will have had a wide range of tests prior to surgery. These include electroencephalography (EEG), in which electrodes are placed on the scalp, on the brain surface, or within the brain to record electrical activity. EEG is used to attempt to locate the focal point(s) of the seizure activity. Several neuroimaging procedures are used to obtain images of the brain. These may reveal structural abnormalities that the neurosurgeon must be aware of. These procedures may include magnetic resonance imaging (MRI), x rays, computed tomography (CT) scans, or positron emission tomography (PET) imaging. Neuropsychological tests may be done to provide a baseline against which the results of the surgery are measured. A Wada test may also be performed. In this test, a drug is injected into the artery leading to one half of the brain, putting it to sleep, allowing the neurologist to determine where language and other functions in the brain are localized, which may be useful for predicting the result of the surgery.

straining may continue to cause headaches or nausea, and should be avoided until the doctor approves. A diet rich in fiber can help avoid constipation, which may occur following surgery. Patients remain on anti-seizure medication at least for the short term, and may continue to require medication.

Risks There is a slight risk of infection or hemorrhage from the surgery, usually less than 1%. Disconnection of the two hemispheres of the brain can cause some neuropsychological impairments such as decreased spontaneity of speech (it may be difficult to bring the right words into one’s mind) and decreased use of the non-dominant hand. These problems usually improve over time. Complete cutting of the corpus callosotomy produces more long-lasting, but very subtle deficits in connecting words with images. These are usually not significant, or even noticed, by the patient. Serious morbidity or mortality occurs in 1% or less of patients. Combined major and minor complication rates are approximately 20%.

Normal results Patients typically experience a marked reduction in number and severity of seizures, with a small percentage of people becoming seizure free. Drop attacks may be eliminated completely in approximately 70% of patients. Other types of seizure are also reduced by 50% or more from corpus callosotomy surgery. Resources BOOKS

Devinsky, O. A Guide to Understanding and Living with Epilepsy. Philadelphia: EA Davis, 1994. ORGANIZATIONS

Epilepsy Foundation. .

Richard Robinson Rosalyn Carson-DeWitt, MD

❙ Corticobasal degeneration

Aftercare The patient remains in the hospital for about a week, possibly more depending on any complications that have occurred during surgery and on the health of the patient. There may be some discomfort afterwards. Tylenol with codeine may be prescribed for pain. Bending over should be avoided if possible, as it may lead to headache in the week or so after the procedure. Ice packs may be useful for pain and itchiness of the sutures on the head. Another several weeks of convalescence at home are required before the patient can resume normal activities. Heavy lifting or

Definition

Corticobasal degeneration (CBD) is a rare, progressive, neurodegenerative disease that causes movement disorders and dementia.

Description CBD occurs when brain cells in two areas of the brain—the cortex and the basal ganglia—die off. The cause of this neurodegeneration is unknown. CBD is also

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callosotomies were performed, and the number has increased since then. Corpus callosotomy is performed by a special neurosurgical team, at a regional epilepsy treatment center.

Craniosynostosis

called cortical basal degeneration and corticobasal ganglionic degeneration.

Demographics It is not known exactly how many people have CBD. In the United States, the number is probably fewer than 10,000. Men and women are equally affected. Symptoms usually appear when a person is 50 or 60 years old.

Causes and symptoms The ultimate cause of CBD is unknown. No genes have been found to be responsible, and no environmental or other risk factors have been identified. The brain areas affected are the cerebral cortex and the basal ganglia. The cerebral cortex is the center of mental activities such as planning, memory, language, and reasoning. The basal ganglia help control movements. The symptoms of CBD may begin with either movement disorders or cognitive disorders. The movement disorders seen in CBD are similar to those in Parkinson’s disease (PD), and CBD is often initially misdiagnosed as PD. In CBD, movements become slow and stiff, and may be accompanied by sustained abnormal postures (dystonia) or sudden violent jerks (myoclonus). Cognitive symptoms include memory impairment, loss of judgment, and difficulty planning or executing movements. Additional features may include impaired speech, and the “alien hand” phenomenon, in which the patient feels disconnected from, and not in control of, a hand or limb. Loss of sensation may also occur.

Key Terms Basal ganglia Brain structure at the base of the cerebral hemispheres involved in controlling movement. Neurodegenerative Relating to degeneration of nerve tissues.

Drugs used against PD are often prescribed, although they are rarely as effective in CBD. These drugs include levodopa and dopamine agonists, as well as anticholinergics such as trihexyphenidyl. Drugs used for Alzheimer’s disease may also be tried for the cognitive symptoms. A speech/language pathologist can help the patient with swallowing difficulties, although over time this problem will become worse and the patient may require the use of a feeding tube. The same specialist can advise about the use of assistive communication devices to improve communication as the ability to speak is lost.

Prognosis Ability to move without a wheelchair is usually lost within five years of diagnosis. Within 10 years, swallowing difficulties often put the patient at risk for developing aspiration pneumonia, or lung infection from food in the airways. Death from pneumonia is common in CBD. Resources WEBSITES

Diagnosis Corticobasal degeneration is diagnosed with a neurological exam (testing of reflexes, coordination, sensation, etc.) and neuroimaging studies, including computed tomography (CT) scan and magnetic resonance imaging (MRI) to detect characteristic loss of brain tissue. Neuropsychological testing is also usually done to determine the kind and degree of cognitive impairment.

WE MOVE. (April 19, 2004.) . National Institute of Neurological Disorders and Stroke (NINDS). Corticobasal Degeneration Information Page. (April 19, 2004). .

Richard Robinson

Cranial arteritis see Temporal arteritis

Treatment team The treatment team includes a neurologist, neuropsychologist, speech/language pathologist, geriatric medicine specialist, and possibly a physical or occupational therapist.

Treatment There are no treatments that can slow or reverse the course of CBD. Some symptoms can be lessened with drugs, although these are inconsistently effective and become less effective as time passes. 244

❙ Craniosynostosis Definition

Craniosynostosis is a defect in which one or more of the flexible and fibrous joints (cranial sutures) between the skull bones closes too soon; it occurs before birth or within a few months after birth. The skull cannot expand normally with growth of the brain, and so assumes an abnormal shape. Craniosynostosis can occur alone or as part of a syndrome of craniofacial defects.

GALE ENCYCLOPEDIA OF NEUROLOGICAL DISORDERS

Cranial sutures The fibrous joints (sutures) that hold together the five bones comprising the skull of a newborn.

Description The skull of a newborn is composed of five bones that are held together by the fibrous sutures positioned at the front, top, sides, and back of the skull. By remaining open, the sutures allow the skull to normally expand in all directions as the brain is growing. The premature closing of one or more of these cranial sutures stops the normal capacity of the skull to expand in early childhood. As not all of the cranial sutures will close, the skull expands in the areas that are still flexible. This results in an abnormally shaped skull or face. The forehead may be very pronounced and inclined forward. Viewed from above, the skull may be more rectangular in shape rather than oval. Other forms of craniosynostosis include coronal craniosynostosis (affecting the coronal suture that crosses the top of the skull from temple to temple), metopic craniosynostosis (affecting the metopic suture of the forehead), sagittal craniosynostosis (affecting the sagittal suture that unites the two parietal bones), and lambdoidal craniosynostosis (affecting the lambdoid suture between the occipital and parietal bones of the skull).

Craniosynostosis can also be caused by maladies that affect the metabolism (rickets, vitamin D deficiency, overactive thyroid) and by bone marrow disorders. Furthermore, some cases have been associated with an abnormally small head (microcephaly) and the accumulation of cerebrospinal fluid in the brain (hydrocephalus). Involvement of the different sutures produces different effects. Closure of the sagittal suture (located at the top of the skull and to the rear) produces an elongated head, prominent and protruding forehead, and narrow temples. Closure of the coronal suture (located on the side of the skull) produces a flattened forehead, higher-than-normal eye socket, abnormal nose, and a skull that slants from side to side. Closure of the metopic suture (which runs down the front-middle portion of the skull) results in a pointed-shaped forehead, triangular-shaped skull, closerthan-normal eyes, and a protruding rear portion of the skull. Finally, closure of the lambdoidal suture (located at the back of the skull) produces a mild flattening of the back of the head, forward-shifted ears, and the coronal symptoms.

Diagnosis Diagnosis is made on the basis of a physical examination.

Demographics Craniosynostosis is a rare occurrence. The sagittal form of the disorder, in which the sagittal suture closes prematurely, is the most common form of craniosynostosis, occurring in three to five of every 1,000 babies, typically males. The frequencies of the various types of craniosynostosis are 50–60% sagittal, 20–30% coronal, 4–10% metopic, and 2–4% lambdoid.

Causes and symptoms Craniosynostosis is usually caused by a genetic mutation. Mutations in several genes (designated TWIST, FGFR-1, FGFR-2, and FGFR-3) have been linked with craniosynostosis. In particular, the protein encoded for by TWIST is critical in the initiation and maintenance of the cranial suture process. As of 2004, the favored hypothesis is that the protein that normally functions to ensure that the formation of the cranial sutures occurs at the right time in development somehow goes awry and causes premature fusion of the bones of the brain.

Treatment team Treatment involves medical specialists (pediatric neurosurgeons, pediatric plastic surgeons, craniofacial surgeons) and specialized nurses.

Treatment Surgery is the common treatment for craniosynostosis. The traditional surgeries involve the exposure of the skull, physical breakage of the fused suture region, and the restoration of the scalp. These surgeries all carry the risks associated with surgery in the brain region. Also, the surgeries produce much bleeding (sometimes a blood transfusion is necessary) and leave a large scar, and transient swelling and bruising can occur. A new surgical technique called endoscopic strip craniectomy has been pioneered by two pediatric surgeons from the University of Missouri Health Care Center. This surgery is much less invasive, produces only a relatively small scar, and leaves little physical after effects

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Key Terms

Research published in 2003 in the Annals of the Royal College of Surgeons of England identified SaethreChotzen syndrome (a rare disorder characterized by an exaggerated forehead and drooping eyelids) as a genetic disorder that produces craniosynostosis.

Craniosynostosis

Beare-Stevenson Cutis Gyrata

Cutis gyrata Craniosynostosis

42y Craniosynostosis Wide-set eyes Developmental delays

Craniosynostosis Protruding eyes Cutis gyrata

35y

d.2y Craniosynostosis, cloverleaf-shaped skull Low-set ears Developmental delays Cutis gyrata

See Symbol Guide for Pedigree Charts. (Gale Group.)

such as swelling and bruising. In the procedure, an endoscope is used to remove the closed suture through incisions that are only several inches in length. In the more than 100 surgeries performed as of January 2001, most of the infants were in a condition satisfactory enough to leave the hospital the following day. Endoscopic strip craniectomy can only be done on infants under six months of age. After the surgery, the baby wears a protective helmet for several months, which molds the growing head into the correct shape.

The outlook for a complete recovery for a child with craniosynostosis depends on whether just one suture is involved or whether multiple sutures have closed. Also, the presence of other abnormalities can lessen the confidence of a satisfactory outcome. Without surgical intervention, craniosynostosis can lead to increased brain pressure, delayed mental development, mental retardation, seizures, or blindness. After surgery is accomplished, the prognosis is excellent. Resources

Recovery and rehabilitation Regardless of the type of surgery performed to correct the defects associated with craniosynostosis, the child will be restricted from vigorous activity or rough play while healing. The protective helmet is required for children after endoscopic strip craniectomy, while permanent plates inserted during other corrective surgeries eliminate the need for the helmet. Children who have had surgery to repair craniosynostosis will continue to need periodic examination by the surgeon until approximately age 18, when the skull has grown to its adult size and shape.

Clinical trials The National Institute for Neurological Diseases and Stroke directly undertakes and funds a range of studies examining the mechanisms of early neurological development. However, there are no clinical trials scheduled to study craniosynostosis as of January 2004. 246

Prognosis

PERIODICALS

Johnson, D. “A Comprehensive Screen of Genes Implicated in Craniosynostosis.” Annals of the Royal College of Surgeons of England (November 2003): 371–377. OTHER

Sheth, R.D. “Craniosynostosis.” eMedicine. January 22, 2004 (March 30, 2004). . National Institute of Neurological Disorders and Stroke. Craniosynostosis Information Page. January 22, 2004 (March 30, 2004). . University of Missouri Health Care. “Craniosynostosis: A New and Better Treatment.” MU Health. January 19, 2004 (March 30, 2004). . ORGANIZATIONS

March of Dimes Birth Defects Foundation. 1275 Mamaroneck Avenue, White Plains, NY 10605. (914) 428-7100 or

GALE ENCYCLOPEDIA OF NEUROLOGICAL DISORDERS

Craniotomy

Bone is sawed at base of flap

Scalp incisions

Cut joining burr holes

Figure A

Figure B

In a craniotomy, the skin over a part of the skull is cut and pulled back. Small holes are drilled into the skull, and a special saw is used to cut the bone between the holes. The bone is removed, and a tumor or other defect is visualized and repaired. The bone is then replaced and the skin closed. (Illustration by Electronic Illustrators Group.)

(888) 663-4637; Fax: (914) 428-8203. askus@ marchofdimes.com. . National Organization for Rare Disorders. 55 Kenosia Avenue, Danbury, CT 06813-1968. (203) 744-0100 or (800) 9996673; Fax: (203) 798-2291. [email protected]. . World Craniofacial Foundation. 7777 Forest Lane, Suite C-621, Dallas, TX 75251-5838. (972) 566-6669 or (800) 533-3315; Fax: (972) 566-3850. worldcf@worldnet. att.net. .

Brian Douglas Hoyle, PhD

❙ Craniotomy

(cerebral aneurysm), to repair arteriovenous malformations (abnormal connections of blood vessels), to drain a brain abscess, to relieve pressure inside the skull, to perform a biopsy, or to inspect the brain.

Demographics Because craniotomy is a procedure that is utilized for several conditions and diseases, statistical information for the procedure itself is not available. However, because craniotomy is most commonly performed to remove a brain tumor, statistics concerning this condition are given. Approximately 90% of primary brain cancers occur in adults, more commonly in males between 55 and 65 years of age. Tumors in children peak between the ages of 3 and 12. Brain tumors are presently the most common cancer in children (4 out of 100,000).

Definition

A craniotomy is a procedure to remove a lesion in the brain through an opening in the skull (cranium).

Purpose A craniotomy is a type of brain surgery. It is the most commonly performed surgery for brain tumor removal. It also may be done to remove a blood clot (hematoma), to control hemorrhage from a weak, leaking blood vessel

Description There are two methods commonly utilized by surgeons to open the skull. Either an incision is made at the nape of the neck around the bone at the back (occipital bone) or a curving incision is made in front of the ear that arches above the eye. The incision penetrates as far as the thin membrane covering the skull bone. During the skin incision, the surgeon must seal off many small blood vessels because the scalp has a rich blood supply.

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Key Terms Abscess A localized collection of pus or infection that is walled off from the rest of the body.

and structures inside the body using a 360° x-ray beam.

Arteriogram An x-ray study of an artery that has been injected with a contrast dye.

Edema An accumulation of watery fluid that causes swelling of the affected tissue.

Arteriovenous malformation Abnormal, direct connection between the arteries and veins. Arteriovenous malformations can range from very small to large. Cerebral aneurysm An abnormal, localized bulge in a blood vessel that is usually caused by a congenital weakness in the wall of the vessel. Cranium Skull; the bony framework that holds the brain. Computed tomography (CT) An imaging technique that produces three-dimensional pictures of organs

The scalp tissue is then folded back to expose the bone. Using a high-speed drill, the surgeon drills a pattern of holes through the cranium (skull) and uses a fine wire saw to connect the holes until a segment of bone (bone flap) can be removed. This gives the surgeon access to the inside of the skill and allows him to proceed with surgery inside the brain. After removal of the internal brain lesion or other procedure is completed, the bone is replaced and secured into position with soft wire. Membranes, muscle, and skin are sutured into position. If the lesion is an aneurysm, the affected artery is sealed at the leak. If there is a tumor, as much of it as possible is resected (removed). For arteriovenous malformations, the abnormality is clipped and the repair redirects the blood flow to normal vessels.

Diagnosis/Preparation Since the lesion is in the brain, the surgeon uses imaging studies to definitively identify it. Neuroimaging is usually accomplished by the following: • Computed tomography (CT) uses x rays and injection of an intravenous dye to visualize the lesion. • Magnetic resonance imaging (MRI) uses magnetic fields and radio waves to visualize a lesion. • An arteriogram is an x ray of blood vessels injected with a dye to visualize a tumor or cerebral aneurysm. Before surgery the patient may be given medication to ease anxiety and to decrease the risk of seizures, swelling, and infection after surgery. Blood thinners (Coumadin, heparin, aspirin) and nonsteroidal antiinflammatory drugs (ibuprofen, Motrin, Advil, Naprosyn, 248

Hematoma An accumulation of blood, often clotted, in a body tissue or organ, usually caused by a break or tear in a blood vessel. Hemorrhage Very severe, massive bleeding that is difficult to control. Magnetic resonance imaging (MRI) An imaging technique that uses magnetic fields and radio waves to create detailed images of internal body organs and structures, including the brain.

Daypro) have been correlated with an increase in blood clot formation after surgery. These medications must be discontinued at least seven days before the surgery to reverse any blood thinning effects. Additionally, the surgeon will order routine or special laboratory tests as needed. The night before surgery the patient should not eat or drink after midnight. The patient’s scalp is shaved in the operating room just before the surgery begins.

Aftercare Craniotomy is a major surgical procedure performed under general anesthesia. Immediately after surgery, the patient’s pupil reactions are tested, mental status is assessed after anesthesia, and movement of the limbs (arms/legs) is evaluated. Shortly after surgery, breathing exercises are started to clear the lungs. Typically after surgery patients are given medications to control pain, swelling, and seizures. Codeine may be prescribed to relieve headache. Special leg stockings are used to prevent blood clot formation after surgery. Patients can usually get out of bed in about a day after surgery and usually are hospitalized for five to fourteen days after surgery. The bandages on the skull are be removed and replaced regularly. The sutures closing the scalp are removed by the surgeon, but the soft wires used to reattach the portion of the skull that was removed are permanent and require no further attention. Patients should keep the scalp dry until the sutures are removed. If required (depending on area of brain involved) occupational therapists and physical therapist assess patients status postoperatively and help the patient improve strength, daily living skills and capabilities, and speech. Full recovery may take up to two months, since it

GALE ENCYCLOPEDIA OF NEUROLOGICAL DISORDERS

Risks The surgeon will discuss potential risks associated with the procedure. Neurosurgical procedures may result in bleeding, blood clots, retention of fluid causing swelling (edema), or unintended injury to normal nerve tissues. Some patients may develop infections. Damage to normal brain tissue may cause damage to an area and subsequent loss of brain function. Loss of function in specific areas can cause memory impairment. Some other examples of potential damage that may result from this procedure include deafness, double vision, numbness, paralysis, blindness, or loss of the sense of smell.

Normal results Normal results depend on the cause for surgery and the patient’s overall health status and age. If the operation was successful and uncomplicated recovery is quick, since there is a rich blood supply to the area. Recovery could take up to eight weeks, but patients are usually fully functioning in less time.

Morbidity and mortality ratesA There is no information about the rates of diseases and death specifically related to craniotomy. The operation is performed as a neurosurgical intervention for several different diseases and conditions.

WHO PERFORMS THE PROCEDURE AND WHERE IS IT PERFORMED?

The procedure is performed in a hospital with a neurosurgery department and an intensive care unit. The procedure is performed by a board certified neurosurgeon, who has completed two years of general surgery training and five years of neurosurgical training.

QUESTIONS TO ASK THE DOCTOR • How is this procedure done? • What kinds of tests and preparation are necessary before surgery? • What risks are associated with the procedure? • How often is normal brain tissue damaged during this type of surgery? • What is the expected outcome of the surgery? • What complications may result from this type of surgery? • What is the recovery time? • How many of these procedures have you done in the past year?

Resources

Expanded Cerebral Hematoma: To What Purpose?” Neurology 58 (May 14, 2002): 1367-1372.

BOOKS

Connolly, E. Sanders, ed. Fundamentals of Operative Techniques in Neurosurgery. New York: Thieme Medical Publishers, 2002. Greenberg, Mark S. Handbook of Neurosurgery. 5th ed. New York: Thieme Medical Publishers, 2000. Miller, R. Anesthesia. 5th ed. Philadelphia, PA: Churchill Livingstone, 2000.

ORGANIZATIONS

American Association of Neurological Surgeons. 5550 Meadowbrook Drive, Rolling Meadows, IL 60008. (888) 566-AANS (2267). Fax: (847) 378-0600. [email protected]. .

Laith Farid Gulli, M.D., M.S. Nicole Mallory, M.S., PA-C Robert Ramirez, B.S.

PERIODICALS

Gebel, J. M. and W. J. Powers. “Emergency Craniotomy for Intracerebral Hemorrhage: When Doesn’t It Help and Does It Ever Help?” Neurology 58 (May 14, 2002): 1325-1326. Mamminen, P. and T. K. Tan. “Postoperative Nausea and Vomiting After Craniotomy for Tumor Surgery: A Comparison Between Awake Craniotomy and General Anesthesia.” Journal of Clinical Anesthesia 14 (June 2002): 279-283. Osguthorpe, J. D. and S. Patel, eds. Skull Base Tumor Surgery. Otolaryngologic Clinics of North America 34 (December 2001). Rabinstein, A. A., J. L. Atkinson, and E. F. M. Wijdicks. “Emergency Craniotomy in Patients Worsening Due to

❙ Creutzfeldt-Jakob disease Definition

Creutzfeldt-Jakob disease (CJD) is a rapidly progressive disease causing damage to the brain. It is one of a group of rare diseases that affects humans and animals, known as transmissible spongiform encephalopathies (TSE) and is believed to be caused by a prion, a newly

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Creutzfeldt-Jakob disease

is common for patients to feel fatigued for up to eight weeks after surgery.

Creutzfeldt-Jakob disease

identified type of disease-causing agent. Creutzfeldt-Jakob disease is characterized by dementia and walking difficulties. Death can occur up to two years after the first symptoms; however, most people die within seven months. There is no treatment or cure.

Encephalopathy A disease or dysfunction of the brain. Myoclonus Twitching muscular contractions.

Description Creutzfeldt-Jakob disease is a serious progressive degenerative disorder of the brain that was first described in the 1920s by two German researchers, and is characterized by sudden development of rapidly progressive neurological and neuromuscular symptoms. When symptoms begin, affected individuals may develop confusion, depression, behavioral changes, impaired vision, and/or impaired coordination. As the disease progresses, there may be rapidly progressive deterioration of thought processes and memory (dementia), resulting in confusion and disorientation, impairment of memory control, personality disintegration, agitation, and restlessness. Affected individuals also develop neuromuscular abnormalities such as muscle weakness and loss of muscle mass (wasting); irregular, rapid, shock-like muscle spasms (myoclonus); and/or relatively slow, involuntary, continual writhing movements, particularly in the arms and legs. Later stages of the disease may include further loss of physical and intellectual functions, a state of unconsciousness (coma), and increased susceptibility to repeated infections of the respiratory tract. In many affected individuals, life-threatening complications may develop less than a year after the disorder becomes apparent. There are three main forms of CJD, each one with its distinctive basic features. The sporadic CJD, which accounts for approximately 85% of all cases worldwide and occurs by chance, is associated with the presence of a misshapen protein in the brain, known as a prion (“proteinaceous infectious particle”). Sporadic CJD cannot be caught from another person or animal, is not related to diet, nor can it be inherited. On the contrary, inherited (or familial) CJD accounts for 5–10% of all cases of CJD and is caused by a faulty gene called prion-related protein (PRPN) that is passed down from parents to their children in a dominant inheritance, which means patients will develop the disease if they inherit a defective gene from just one parent. Symptoms are similar to sporadic CJD, but they appear earlier and have a longer time course. Unlike the previous two CJD forms, acquired CJD affects those people who have not inherited the condition by two other ways. The iatrogenic CJD occurs due to accidental infection after medical procedures such as human pituitary hormone injection or dura mater transplantation. The variant CJD (vCJD), a type of CJD that was first identified in 1996, is passed from cows with bovine spongiform encephalopathy (BSE, or “mad cow disease”) to 250

Key Terms

Prion A protein particle lacking nucleic acid and thought to be the cause of certain infectious diseases of the central nervous system, such as CreutzfeldtJakob disease.

humans. The variant form affects mostly younger adults and has different clinical and pathological characteristics. All forms of CJD can be present in a person for long periods (often more than 20 years) during which there are no symptoms. The duration of the illness before death varies from a matter of weeks (typical of sporadic CJD) to three to twelve months (typical of variant CJD). However, there have been exceptions in both types.

Demographics CJD appears to affect males and females in equal numbers. It occurs worldwide with an incidence rate that has remained stable at approximately one case per million people, annually. It usually first appears in mid-life, beginning between ages 20 and 68, with the average age at onset of symptoms being around age 50. The onset of the iatrogenic form depends on the age of exposure.

Causes and symptoms All forms of CJD are caused by the presence of a faulty protein in the brain, called prion. Prions occur in both a normal form, which is a harmless protein found in the body’s cells, and in an infectious form, which causes disease. The harmless and infectious forms of the prion protein are nearly identical, but the infectious form takes a different folded shape. Sporadic CJD may develop because some of a person’s normal prions spontaneously change into the infectious form of the protein and then alter the prions in other cells in a chain reaction by a mechanism that is not yet understood. Misfolded protein molecules then spread through the brain and stick together to form fibers and/or clumps called plaques that can be seen with powerful microscopes. These bundles of twisted protein disrupt brain cells and eventually leave large holes in the brain tissue, giving the brain a spongy appearance. Fibers and plaques may start to accumulate years before symptoms of CJD begin to appear. It is still unclear what role these abnormalities play in the disease or how they might affect symptoms.

GALE ENCYCLOPEDIA OF NEUROLOGICAL DISORDERS

Diagnosis There is currently no single diagnostic test for CJD. Indeed, the only definitive diagnosis can be assessed by a postmortem examination (autopsy) of the brain or examining a sample of brain tissue (brain biopsy). However, CJD should be considered in adults who experience a sudden onset of rapidly progressive dementia and neuromuscular symptoms such as myoclonus. An electroencephalogram (EEG) and a magnetic resonance imaging (MRI) scan may be useful in determining abnormalities in the brain. People may be diagnosed as having “probable CJD.” Although not definitive, all those who have been diagnosed as probable CJD in life, and who subsequently had an autopsy, were found to have been a CJD patient. Genetic testing can be carried out in people suspected of having the inherited form of CJD, in order to increase certainty of diagnosis. Such people usually report a family history of the disease. Iatrogenic CJD is usually diagnosed on the basis of the affected person’s medical history. Those at risk include people having received hormones derived from humans before 1992, or dura mater transplant grafts before 1985.

Treatment team A neurologist or a psychiatrist is normally the primary consultant for CJD, and continual nursing care may be necessary as disease progresses. Physical therapist may also be required.

Treatment As of 2004, no treatment has been shown to be effective against CJD. Treatments are available to alleviate some symptoms, such as morphine for muscle pain, and clonazepam (Rivotril) or sodium valproate (Epilim) for jerky movements. A wide range of drugs has been tested for their ability to slow the progress of the disease, but none has been shown to be useful. At present, care consists of managing the specific problems faced by patients with CJD. Speech therapy and occupational therapy may help, and the support of district nurses and social services is often invaluable for people with CJD and their caregivers.

Recovery and rehabilitation Because CJD is an incurable, fatal disease with a fast progression, recovery and rehabilitation are not possible. The emphasis in treatment is placed upon comfort and support of the affected individual and the caregivers.

Clinical trials As of mid 2004, there are no ongoing clinical trials for CJD.

Prognosis The outcome for a person with CJD is usually very poor. Complete dementia commonly occurs within six months or less after the appearance of the first symptoms, with the person becoming totally incapable of self-care. The disorder is fatal in a short time, usually within seven months, but a few people survive as long as one or two years after diagnosis. The cause of death is usually infection, heart failure, or respiratory failure.

Special concerns Hospitals and health care providers take special precautions to minimize the risk of transferring prions from surgical equipment or donated tissues. Medical histories of potential cornea donors that indicate a familial history of possible Creutzfeldt-Jacob disease rule out the use of those corneas for transplantation. Additionally, regulations and records regarding livestock feed and transfer of livestock are maintained by the United States Department of Agriculture.

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About 5–10% of all CJD cases are inherited. These cases arise from a mutation, or change, in the gene PRPN that controls formation of the normal prion protein. While prions themselves do not contain genetic information and do not require genes to reproduce themselves, infectious prions can arise if a mutation occurs in the gene for the body’s normal prions. If the prion gene is altered in a person’s sperm or egg cells, the mutation can be transmitted to the person’s offspring. Several different mutations in the prion gene have been identified. The particular mutation found in each family affects how frequently the disease appears and what symptoms are most noticeable. However, not all people with mutations in the prion gene develop CJD. This suggests that the mutations merely increase susceptibility to CJD and that other, still-unknown factors also play a role in the disease. CJD does not cause any symptoms at first. The first symptoms to appear include slow thinking, difficulty concentrating, impaired judgment, memory loss, personality and behavioral changes, and difficulties with coordination and vision. These symptoms rapidly give way to increasing mental deficits leading to severe, progressive dementia (mental decline) associated with self-neglect, apathy or irritability, and prominent muscle spasms (myoclonus). Seizures commonly occur as the disease progresses. Symptoms continue to worsen until both mental and physical functions are lost; patients are completely bedridden, and eventually lapse into coma. Comatose patients may die as a result of infection associated with being immobile, such as pneumonia.

CT scan A patient about to undergo a CAT scan to check for brain cancer. (© Roger Ressmeyer/CORBIS. Reproduced by permission.)

Resources BOOKS

Staff. The Official Patient’s Sourcebook on Creutzfeldt-Jakob Disease: A Revised and Updated Directory for the Internet Age. San Diego: Icon Group International, 2003. PERIODICALS

Mastaglia, F. L., M. J. Garllep, B. A. Phillips, and P. J. Zilko. “Inflammatory Myopathies: Clinical, Diagnostic and Therapeutic Aspects.” Muscle & Nerve (April 2003): 407–425. “U.S. to Expand Testing of Cattle for Disease.” New York Times March 16, 2004: pA25.

Definition

Computed tomography (also known as CT, CT scan, CAT, or computerized axial tomography) scans use x rays to produce precise cross-sectional images of anatomical structures.

Description

OTHER

“New ‘Mad Cow’ Link to Humans and Livestock.” CNN.com. August 29, 2000 (May 27, 2004). . NINDS Creutzfeldt-Jakob Disease Information Page. National Institute of Neurological Disorders and Stroke. April 20, 2004 (May 27, 2004). . ORGANIZATIONS

Creutzfeldt-Jakob (CJD) Foundation Inc. P.O. Box 5312, Akron, OH 44334. (330) 668-2474 or (800) 659-1991. [email protected]. .

Marcos do Carmo Oyama Iuri Drumond Louro, MD, PhD 252

❙ CT scan

With the development of modern computers, the scans enhanced digital capabilities allowed the development of computed tomography imaging (derived from the Greek tomos, meaning “to slice”). The diagnostic potential of CT scans was first realized by English physician Godfrey Hounsfield. CT scans differ from conventional x ray by collecting x rays that have passed through the body (those not absorbed by tissue) with an electronic detector mounted on a rotating frame rather than on film. The x-ray source and collector rotate around the patient as they emit and absorb x rays. CT technology then utilizes advanced computerbased mathematical algorithms to combine different readings or views of a patient into a coherent picture usable for diagnosis.

GALE ENCYCLOPEDIA OF NEUROLOGICAL DISORDERS

Computerized axial tomographic (CAT) scan A scanning method, also called CT scanning, that uses diagnostic x rays and a computer to give crosssectional images at different angles of the brain and other parts of the body. Radiologist A physician who specializes in imaging techniques such as x rays, CAT scans, MRI scans, and certain scans using radioactive isotopes. X ray Electromagnetic radiation of very short wavelength, and very high energy.

CT scans increase the scope and safety of imaging procedures that allow physicians to view the arrangement and functioning of the body’s internal structures. With particular regard to neurology, CT scans are used to determine the presence or absence of brain tumors. CT scans usually take about an hour and a half, including preparation time, with the actual examination of neural tissue in a brain scan taking 15–45 minutes. CT scanners are now often combined with positron emission tomography (PET) scanners into one unit. PETCT scanners have the ability to link the functional image created by a PET scan with the anatomical image produced by a CT scan. The combined scanning technique enhances a physician’s ability to detect metabolic abnormalities (some no larger than 0.15 in [4 mm] in size) and to precisely map the location of the anomaly. Increased accuracy reduces the number of unusable results and also results in less retesting. The combined PET-CT scanners offer physicians the opportunity to differentiate, for example, between Alzheimer’s disease and multi-infarct dementia. In addition, the enhanced images allow the differentiation of brain tumors from cerebral necrosis.

The physics The physical basis of the CT scans lies in the fact that different tissues absorb x rays at different rates. The density and atomic number of the elements present are critical factors in determining whether a particular x ray is absorbed or passes through the body. The opacity of an image is related directly to the type of tissue or element. Dense bone appears white, while gaseous air in the lungs appears black. CT scans are also used by some security agencies to examine packages and baggage.

CT scan allow the construction of detailed images and offer another, and in many cases, more affordable means of diagnosis without invasive surgical procedures. CT scans can also be used to guide the course of surgical procedures. CT scans often utilize a medium or contrast enhancer, provided in the form of a drinkable liquid or via injection into the patient’s bloodstream. Approximately 45 minutes before a patient is examined, the individual is given an intravenous injection of a radiopharmaceutical tracer. A brain scan and scan of the spinal cord can take less than 30 minutes. Radiation exposure from a CT exam is roughly equal to a normal year’s worth of exposure to natural background radiation—more than from a conventional x-ray examination, but less than that of other x-ray exams such as a skull x ray. Because x rays are high energy rays that can damage critical cells in the developing embryo, women who suspect that they are pregnant should inform their doctor and the CT scan technologist prior to the exam. Nursing mothers are often advised to wait 24 hours after the injection of the contrast medium before resuming breast-feeding. Because CT scans provide only axial cross-sections, an MRI test is often used to more carefully examine unusual or suspect findings. Resources WEBSITES

“Computed Tomography.” EcureME. May 9, 2004 (May 27, 2004). . The CT: Computed Tomography Test. University of Iowa Department of Neurology. May 9, 2004 (May 27, 2004). .

Paul Arthur

Cumulative trauma disorders see Repetitive motion disorders

❙ Cushing syndrome Definition

Cushing syndrome was first described by an American neurosurgeon in the early twentieth century named Harvey Cushing. Cushing recognized a specific set of symptoms that collectively he identified as part of a syndrome. In this disease, prolonged exposure to abnormal

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Cushing syndrome

Key Terms

CT scan procedures

Cushing syndrome

levels of the hormone cortisol results in the collection of symptoms that Harvey Cushing described. Cushing Syndrome can also be associated with abnormal levels of another hormone, adrenocorticotropin (ACTH), and both ACTH and cortisol overproduction can often occur as part of other disorders.

Description Cushing syndrome affects the body in many ways and can lead to severe medical complications if untreated. Effects of the disorder are manifested clinically, physically, and emotionally. Physically, patients develop an abnormal fat distribution that sometimes leads to feelings of insecurity or unattractiveness. Clinically, people with Cushing syndrome are often at risk for a variety of significant medical problems including diabetes, high blood pressure, hair loss (especially in women), and heart disease. Cushing syndrome is relatively rare. Severe fatigue can also develop and this has many ramifications in terms of complications related to daily living. Cushing syndrome is sometimes referred to as hypercortisolism.

Demographics According to the National Institute of Diabetes & Digestive & Kidney Diseases (NIDDK), an estimated 10 to 15 individuals out of every million people will be affected each year with Cushing syndrome. These individuals are usually adults between the ages of twenty to fifty years old. Pituitary adenomas cause the majority of Cushing syndrome cases, and women that have these types of tumors are at a five-fold higher risk for developing the disease than men.

Causes and symptoms The function of cortisol is to regulate blood pressure, act as an anti-inflammatory mediator, and to regulate insulin metabolism. Cortisol plays a role during the metabolic activities associated with fat, protein, and carbohydrate metabolism. High levels of cortisol can cause sodium and water retention. Therefore, overproduction of cortisol can have medically important health-related implications that affect muscle contractions, heartbeat, and blood cell function. The adrenal glands are located on top of each kidney, and are responsible for releasing cortisol. The site of cortisol production is in the outer layer of the adrenal gland called the adrenal cortex. Release of cortisol is stimulated by ACTH, which is produced by another gland. This gland, called the pituitary gland, is juxtaposed to the base of the brain and serves as a type of control center for many other glands in the body. ACTH production occurs only when there is a low concentration of cortisol in the blood. 254

Therefore, cortisol production can be abnormal due to abnormalities in the function of the adrenal gland or the pituitary gland. It can also be overproduced by abnormal regulation of ACTH. The role of cortisol in tumor formation Cortisol overproduction can also be caused by many different types of tumors resulting in abnormalities in the function or regulation of the adrenal or pituitary glands. These tumors are usually not malignant and are found in the pituitary and adrenal glands. In the pituitary gland, a specific type of tumor called an adenoma can develop. Pituitary adenomas often can excessively overproduce ACTH in the absence of the normal stimulatory signals. People that develop Cushing syndrome are most likely to develop this disease due to these types of tumors. ACTH overproduction can also occur when the tumor is located outside of the pituitary gland; this condition is known as ectopic ACTH syndrome. These tumors, unlike pituitary adenomas, tend to be cancerous. Tumors can also develop in the adrenal gland and result in excessive cortisol production. Adrenal tumors can often result in malignancy, and patients with these tumors often quickly become symptomatic due to the high levels of cortisol produced. Familial Cushing syndrome Cushing syndrome can also develop in multiple individuals from the same family. This familial form is due to a genetically inherited susceptibility to developing specific endocrine tumors. The specific nature of the genetic components have not been clearly elucidated, except in cases of a rare genetic disease called Multiple Endocrine Neoplasia (MEN). MEN is caused by a genetic mutations in a specific gene involved in cell cycle regulation resulting in pituitary tumors that can lead to Cushing syndrome. The symptoms associated with Cushing syndrome can be easily recognizable by an experienced physician. These clinical manifestations include physical characteristics that involve the face, neck, shoulders, and abdomen. Generally, most affected individuals develop obesity of the upper portion of their bodies. They often have thin arms and legs. The facial feature that characterizes Cushing syndrome is the typically developed round, moon-shaped face. An accumulation of fat pads are often observed on or below the base of the neck, on the patients back, between the patient’s shoulders, as well as on the abdomen. Abdominal fat accumulation can be significant and can also be associated with vertical purplish striations (stretch marks). Stretch marks also can be observed on their thighs, arms, breasts, and buttocks. Affected children often suffer from obesity along with growth retardation. Other clinical manifestations resulting from excessive cortisol production can be quite serious. Myopathy, or

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Adrenocorticotropic hormone (ACTH) Also called adrenocorticotropin or corticotropin, this hormone is produced by the pituitary gland to stimulate the adrenal cortex to release various corticosteroid hormones. Cortisol A steroid hormone secreted by the adrenal cortex that is important for maintenance of body fluids, electrolytes, and blood sugar levels. Also called hydrocortisone. Pituitary gland The most important of the endocrine glands (glands that release hormones directly into the bloodstream), the pituitary is located at the base of the brain. Sometimes referred to as the “master gland,” it regulates and controls the activities of other endocrine glands and many body processes including growth and reproductive function. Also called the hypophysis.

Treatment team Several types of medical doctors are usually required for the diagnosis and treatment of Cushing syndrome. This includes an oncologist, a pathologist, or an endocrinologist. Although it is unlikely that a child would develop this disease, treatment would depend on whether the child has progressed through puberty. As Cushing syndrome in children can result in growth retardation, a pediatric endocrinologist would be the most likely specialist to monitor the child’s development.

Treatment wasting away of the muscles often occurs. Due to the abnormal blood cell development that results from cortisol overproduction, the skin bruises more frequently and wounds do not heal as quickly. Skin tends to be fragile and thin. People with Cushing syndrome are susceptible to developing fractures, especially in the pelvic and spinal regions. Women are at a higher risk for developing osteoporosis or brittle bones. Men also frequently develop weak bones. For all affected individuals, difficulty with activities such as lifting objects or getting up from a sitting position can lead to back pain and fractures. Because cortisol is also important for regulating insulin, patients with Cushing syndrome are at risk for developing diabetes.

Diagnosis The diagnosis of Cushing syndrome is based on the patient’s family history and the results from several laboratory tests. The most definitive diagnostic laboratory test is to monitor cortisol production in the person’s urine during a 24-hour collection period. A 50–100 microgram result represents the normal cutoff, with any higher value suggestive of Cushing syndrome. When cortisol is found to be high, x rays are usually requested to identify pituitary or adrenal tumors. A dexamethasone suppression test is often requested with a positive finding on x ray and is used to distinguish between ACTH overproduction due to pituitary adenomas or other tumors. Dexamethasone is a synthetic hormone that, when used to help diagnose Cushing syndrome, is usually orally administered for four days at increasing

Determining the appropriate treatment for individuals with Cushing syndrome relies on the accurate determination of the cause of excessive cortisol production. As there are a variety of causes, selecting the appropriate treatment depends on characterizing the disease based on the precipitating spectrum of clinical manifestations. For example, abnormal function of the pituitary gland or the adrenal cortex can be important indicators of causation. For this reason, it is important that affected individuals have a comprehensive clinical evaluation by an experienced physician. Tumors of the pituitary gland or the adrenal cortex can stimulate overproduction of ACTH or cortisol. Medical treatments with cortisone for unrelated conditions may also alter the amount of cortisol exposure and concentration circulating within the body. In cases that involve pituitary tumors as the cause of Cushing syndrome, surgical removal represents a formidable treatment in cases where chemotherapy or radiation is ineffective. Transsphenoidal adenomectomy, a surgical procedure, is the most widely used treatment for pituitary adenomas that cause Cushing syndrome. This usually requires a specialized surgeon or treatment center, as it is a relatively rare and difficult procedure. The success rate is high and synthetic hormone replacement therapy, typically with prednisone, is only necessary for approximately one year. As an alternative, radiation therapy is also a possibility. There are also therapeutic agents that inhibit cortisol production that can be used. Adrenal gland tumors are usually always surgically removed, whether they are benign or malignant. Adrenal gland removal typically does not affect endocrine function

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dosages, during which time the urine is collected. The effect on blood and urine cortisol concentrations can be determined and the different effects can distinguish these two types of ACTH-producing tumors. Radiological imaging such as MRI scans sometimes allow endocrinologists (physicians who specialize in hormone-related health concerns) to directly visualize the glands and determine their size and shape.

Cytomegalic inclusion body disease

due to compensation from other glands in producing hormones. Hormone therapy is required with removal of both adrenal glands. If the cause of Cushing syndrome is drug-induced, due to prolonged exposure to steroids called glucocorticoids that are used to treat other ailments, the physician will lower this dose as long as symptoms continue to be manifested.

Recovery and rehabilitation Transsphenoidal adenomectomy performed by an experienced surgeon has a high success rate, with more than 80% of patients cured. In the event that the surgery is not successful or it provides only a temporary cure, it is often repeated with fairly favorable results. For radiation therapy, adding one of many drugs that suppresses cortisol production such as mitotane can enhance recovery time. These drugs have been considered to be effective when used alone in up to 40% of patients. As scientists and clinicians better understand how cortisol and ACTH are produced and how disturbances in hormonal regulation affect the body, more treatment modalities will likely become available.

Clinical trials The National Institutes of Health sponsors several scientists in clinical translational research in Cushing syndrome treatment, as well as the development of drugs leading to clinical trials. As of early 2004, there were at least eight ongoing clinical trials recruiting patients. These include long term post-operative follow ups, the evaluation of novel imaging techniques, understanding the role of stress and depression in Cushing syndrome, and other studies investigating adrenal and pituitary gland tumors. Further information on clinical trials can be found at the National Institutes of Health website on clinical trials, ClinicalTrials.gov, available at: .

Prognosis The prognosis for individuals who receive treatment for Cushing syndrome is good with a high likelihood of being cured. However, in affected individuals that are not treated, the prognosis can be poor, with death eventually resulting from complications from hypertension, diabetes, or heart disease. Resources BOOKS

Icon Health Publications. The Official Patient’s Sourcebook on Cushing’s Syndrome: A Revised and Updated Directory for the Internet Age. San Diego: Icon Group, Int., 2002. 256

DeGroot, Leslie J., ed., et al. “Cushing’s Syndrome.” In Endocrinology, Vol. 2, pp. 1741–1769. Philadelphia: W. B. Saunders Company, 1995. Wilson, Jean D., ed, et al. “Hyperfunction: Glucocorticoids: Hypercortisolism (Cushing’s syndrome),” pp. 536–562. In Williams Textbook of Endocrinology, No. 8. Philadelphia: W. B. Saunders, 1992. PERIODICALS

Boscaro, M., L. Barzon, F. Fallo, and N. Sonino. “Cushing Syndrome.” Lancet 357, no. 9258 (March 10, 2001): 783–91. OTHER

NINDS Cushing’s Syndrome Information Page. National Institute of Neurological Disorders and Stroke. (January 20, 2004.) . Cushing’s Syndrome. National Institute of Diabetes & Digestive & Kidney Diseases. (January 20, 2004). . ORGANIZATIONS

Cushing’s Support and Research Foundation, Inc. 65 East India Row 22B, Boston, MA 02110. (617) 723-3824 or (617) 723-3674. [email protected]. . Pituitary Network Association. P.O. Box 1958, Thousand Oaks, CA 91358. (805) 499-9973; Fax: (805) 480-0633. [email protected]. .

Bryan Richard Cobb

❙ Cytomegalic inclusion body disease

Definition Cytomegalic inclusion body disease (CIBD) is a condition caused by infection with cytomegalovirus (CMV), a type of herpes virus. A hallmark of CIBD is the periodic reappearance of symptoms throughout life, as the virus cycles through periods of latency and active infection.

Description CMV is one of the members of the herpes virus group, which includes herpes simplex types 1 and 2, and the viruses that cause chicken pox and infectious mononucleosis. The virus causes enlargement of cells of some organs and the development of inclusion bodies—bits of cellular material—in the cytoplasm or nucleus of these cells. A hallmark of the virus group is the ability to infect a host and then become dormant. CMV can remain dormant for years. Even in periods without symptoms, the

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Cytomegalovirus A member of the herpes virus group found throughout all geographic locations and socioeconomic groups; virus usually remains dormant throughout life, reactivating when the body’s immune system is severely debilitated. Immunocompromised An abnormal condition in which the body’s ability to fight infection is decreased, due to a disease process, certain medications, or a condition present at birth. Inclusion body A small intracellular body found within the cytoplasm or nucleus of another cell, characteristic of disease.

The latent infection caused by CMV occurs virtually all over the world and is very common in any population. In the United States, up to 50–85% of people will be infected by the age of 40. CMV infection without symptoms is common in infants and young children. CMV infection is most widespread in economically debilitated regions, although people in developed countries are also susceptible. Additionally, the virus can be readily transferred from a pregnant mother to the fetus. An infected pregnant woman may not display any symptoms. However, the fetus of a mother with CIBD is at risk for problems, including lung disease, bleeding, anemia, liver damage, or brain damage. CIBD is also a problem among those whose immune systems are not functioning properly or have not yet matured. This includes the unborn, people infected with the human immunodeficiency virus (HIV), and those whose immune systems have been deliberately disabled (i.e., organ transplant recipients).

Causes and symptoms The cytomegalovirus is the cause of CIBD. When the infection occurs in healthy people after birth, symptoms can be minimal or even nonexistent. Some people experience mild symptoms similar to those of mononucleosis, including a prolonged fever, fatigue, mild hepatitis, and tender lymph nodes. In a fetus, newborn, or a person with a compromised immune system, CIBD can be much more severe. With CIDB, people suffering from acquired immunodeficiency syndrome (AIDS) or people recovering from kidney and or other transplant surgeries can also develop inflammation of the retina of the eyes (retinitis) or encephalitis. Retinitis is more common, and in severe cases, blindness can result.

Part of the cytomegalovirus. (CNRI / Photo Researchers, Inc.)

CIBD can cause death of a fetus or a premature birth. In infected newborns, CIBD can be apparent as a lung infection, excessive bleeding, anemia, liver damage, enlargement of the spleen, seizures, and inhibited brain development. The latter can result in hearing loss, developmental delays, and difficulty in coordination.

virus can still be periodically shed from the body in fluids like tears, saliva, blood, semen, and breast milk. The virus can infect another person through close contact.

CMV-related polyradiculopathy also causes leg weakness, bowel dysfunction, and bladder dysfunction in end-stage AIDS patients suffering CMV infection.

Many people with CMV can harbor the virus and display no symptoms. However, if the immune system is damaged or otherwise not functioning efficiently, the virus can reactivate from its dormancy. Cytomegalic inclusion body disease is also known as giant cell inclusion disease, cytomegalovirus infection, and salivary gland disease.

Diagnosis Diagnosis is based on the detection of the symptoms of CIBD. Because symptoms can be absent, diagnosis is often overlooked or difficult. If the virus is actively dividing, antibodies to the virus may be detectable by immunological tests of the blood such as the enzyme-linked

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Key Terms

Demographics

Cytomegalic inclusion body disease

immunosorbant assay (ELISA). As the antibodies persist for life, their detection is not a guarantee of an ongoing infection. The virus can also be isolated from urine and other body fluids. One diagnostic feature associated with retinitis is the description of moving black spots in the eye. Although these “floaters” are common even in healthy individuals, they can also be the result of inflammation of the retina, and can alert a physician to the possibility of CIBD.

Treatment team

Resources BOOKS

Parker, J. N., and P. M. Parker. The Official Patient’s Sourcebook on Cytomegalic Inclusion Body Disease. A Revised and Updated Directory for the Internet Age. San Diego: Icon Health Publications, 2003. OTHER

Treatment is usually maintained by the primary care physician for otherwise healthy patients. For those who are deliberately immunocompromised, newborns, and AIDS patients, a battery of specialists, including immunologists and specialists in infectious disease, can be involved in treatment and care.

Treatment There is no cure for CIBD. Typically, good hygiene, including proper hand washing, is recommended to avoid transmission of the virus from person to person. Antiviral drugs such as ganciclovir and acyclovir can be administered, particularly to AIDS patients to reduce the amount of virus in the body. These drugs are taken throughout life. There are no vaccines for CIBD.

Recovery and rehabilitation The CMV infection persists throughout life, therefore, rehabilitation efforts focus on supportive measures to combat CMV-caused complications, minimize the effect of symptoms, and minimize the possibility for transmission of the virus.

Clinical trials As of February 2004, there are no specific CIBD clinical trials underway.

Prognosis Most people who are infected with CMV display no symptoms and have no residual effects of the infection.

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However, in immunocompromised people, newborns, and unborn babies, the infection can cause serious illness or death.

Cytomegalic Inclusion Body Disease Information Page. National Institute of Neurological Disorders and Stroke. (May 20, 2004). . Cytomegalovirus (CMV). New Mexico AIDS InfoNet. (May 20, 2004). . Cytomegaolavirus (CMV) Infection. Centers for Disease Control and Prevention. (May 20, 2004). . ORGANIZATIONS

Centers for Disease Control and Prevention (CDC). 1600 Clifton Road, Atlanta, GA 30333. (404) 639-3311 or (800) 311-3435. . National Institute of Allergy and Infectious Disease (NIAID). 31 Center Drive, Rm. 7A50, MSC 2520, Bethesda, MD 20892-2520. (301) 402-1663; Fax: (301) 402-0120. [email protected]. . National Institute for Neurological Diseases and Stroke (NINDS). 6001 Executive Boulevard, Bethesda, MD 20892. (301) 496-5751 or (800) 352-9424. .

Brian Douglas Hoyle, PhD

Cytomegalovirus infection see Cytomegalic inclusion body disease

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D Dancing eyes-Dancing feet syndrome see Opsoclonus myoclonus

❙ Dandy-Walker syndrome Definition

Dandy-Walker syndrome refers to a group of specific, congenital (present at birth) brain malformations, and is a common cause of hydrocephalus (increased fluid in the brain).

Description Dandy-Walker syndrome is more often referred to as Dandy-Walker malformation (DWM) or Dandy-Walker complex. The condition is named for doctors Walter E. Dandy and Arthur E. Walker, who described the signs and symptoms of the condition in the early 1900s. The brain contains four ventricles, which are inner, hollow portions filled with cerebrospinal fluid (CSF). The first and second (lateral) ventricles are inside the cerebral hemispheres, and the third and fourth ventricles are below them, closer to the brainstem. DWM consists of a specific group of brain malformations, including enlargement of the fourth ventricle, complete or partial agenesis (lack of development) of the cerebellar vermis (the middle portion of the cerebellum, which lies directly behind the cerebral hemispheres), and cyst formation and dilation of the posterior fossa (a small, hollow section between the lower cerebellum and skull). A further defining characteristic of DMW is blockage or closure of the foramina (openings) of Magendie and Luschka, two channels at the base of the brain through which CSF normally flows. When these openings are obstructed, CSF produced in the ventricles has no outlet for normal circulation. This causes fluid pressure to build, and the ventricles to enlarge (always the fourth, and often the third and lateral ventricles).

Demographics About one in 1,000 children is born with hydrocephalus. Of those, 10% have DWM as the underlying cause of their condition. DWM has not been shown to be more frequent in any particular ethnic group or race. About 85% of babies born with DWM have one or more other congenital malformations, or some type of recognizable syndrome. The 15% that have no other malformations may be said to have “isolated” DWM.

Causes and symptoms The true cause of DWM is unknown. However, the components of the malformation seem to be related to a disruption in development of the middle portion of the lower part of the brain in the embryonic stage. This affects growth and development of the cerebellum, especially the vermis, and the brainstem such that the foramina of Magendie and Luschka are partially or completely closed. Most cases of isolated DWM occur by chance (sporadic) and have very little risk of recurrence in siblings or children of the affected individual. In a few cases, DWM may be inherited as an autosomal recessive trait, which would imply a 25% risk for recurrence in siblings. Some syndromes that may occur with DWM are chromosomal (abnormal number of chromosomes in every cell of the body—usually sporadic), while others are hereditary. The empiric recurrence risk for non-syndromic DWM with other anomalies is about 5% for siblings or children of the affected individual. Outward physical signs of DWM may be a bulging occiput (lower rear portion of the skull) and an increased total head circumference. Symptoms of DWM are those caused by hydrocephalus (if present) and dysgenesis/agenesis of the cerebellar vermis. In infants, symptoms can include irritability, seizures, vomiting, abnormal breathing, nystagmus (jerky eye movements), and slow motor development. Older children and adults may have headaches, ataxia (difficulties with coordination), visual disturbances, and/or developmental delay/mental retardation.

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Treatment

Key Terms Cerebellum The part of the brain involved in the coordination of movement, walking, and balance. Cerebrospinal fluid The clear, normally colorless fluid that fills the brain cavities (ventricles), the subarachnoid space around the brain, and the spinal cord and acts as a shock absorber. Hydrocephalus An abnormal accumulation of cerebrospinal fluid within the brain. This accumulation can be harmful by pressing on brain structures, and damaging them. Ventricles The four fluid-filled chambers, or cavities, found in the two cerebral hemispheres of the brain, at the center of the brain, and between the brain stem and cerebellum, and linked by channels, or ducts, allowing cerebral fluid to circulate through them. Ventriculoperitoneal shunt A tube equipped with a low-pressure valve, one end of which is inserted into a cerebral ventricle, the other end of which is routed into the peritoneum, or abdominal cavity.

Diagnosis DWM may be diagnosed in pregnancy by ultrasound as early as 12–14 weeks after conception, although ultrasounds later in pregnancy are more sensitive. A level II ultrasound, a more detailed examination that can only be performed 18 weeks or later after conception, may be suggested to confirm the diagnosis of DWM and will look for the presence of other malformations. An amniocentesis, a procedure to analyze fetal chromosomes, is also usually offered. After birth, DWM may be suspected because of physical or neurological signs, but it is only possible to establish the diagnosis of DWM by performing imaging studies of the brain through a computed tomography (CT) scan or magnetic resonance imaging (MRI).

Treatment team A neurosurgeon would perform any surgical procedures (such as shunts) needed to help relieve hydrocephalus or intracranial cysts. Depending on the severity of any neurological symptoms and the presence or absence of other congenital malformations, various specialists involved in the care of a child with DWM can include a neonatologist (specialist in the care of newborns), developmental pediatrician, geneticist, neurologist, specialized nursing care, and occupational/physical therapists (OT/PT). 260

The primary treatment for DWM and associated hydrocephalus is the placement of a ventriculoperitoneal (VP) shunt. This is a procedure in which a neurosurgeon places one end of a small tube in a ventricle in the brain, and threads the other end under the skin down to the peritoneal (abdominal) cavity. The tube helps to direct excess CSF to the peritoneal cavity where it is reabsorbed by the body. In some cases, the neurosurgeon may attempt a procedure called endoscopic fenestration. In this procedure a small, flexible viewing device, called an endoscope, is inserted into the brain and an opening is made between the third and fourth ventricles or in the foramina at the base of the brain. It is hoped that opening these passages will equalize CSF pressure throughout the central nervous system. Other treatments include those for the symptoms of hydrocephalus and cerebellar agenesis, such as anti-seizure medications, and OT/PT for neuromuscular problems.

Recovery and rehabilitation Some children recover completely after a shunt is placed, while others receive partial benefit. Shunting procedures are not always successful, and they carry a risk for serious infection. A child who retains neurologic deficits will likely require long-term care by a neurologist and OT/PT. Special accommodations for home care may also be needed.

Clinical trials There are no clinical trials for Dandy-Walker syndrome.

Prognosis Prognosis for DWM varies anywhere from excellent to fatal. The overall prognosis for DWM that occurs and is diagnosed as part of a known syndrome will depend on the possible prognoses for that particular syndrome, although the presence of DWM may have a negative impact. In other cases, DWM without other anomalies has a much better prognosis. As noted, prognosis is also critically dependent on the degree of hydrocephalus already present at birth or at the time of diagnosis. Resources BOOKS

Volpe, Joseph, J. Neurology of the Newborn, 4th edition. Philadelphia: W.B. Saunders Company, 2001. PERIODICALS

Ecker, Jeffrey L., et al. “The Sonographic Diagnosis of DandyWalker and Dandy-Walker Variant: Associated Findings and Outcomes.” Prenatal Diagnosis 20 (2000): 328–332.

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OTHER

NINDS Dandy-Walker Syndrome Information Page. The National Institute of Neurological Disorders and Stroke. April 2, 2003 (March 30, 2004). . ORGANIZATIONS

Dandy-Walker Syndrome Network. 5030 142nd Path W, Apple Valley, MN 55124. (952) 423-4008. Hydrocephalus Association. 870 Market Street, Suite 705, San Francisco, CA 94102. (888) 598-3789; Fax: (415) 7327044. . Hydrocephalus Research Foundation. 1670 Green Oak Circle, Lawrenceville, GA 30243. (770) 995-9570; Fax: (770) 995-8982. Hydrocephalus Support Group, Inc. PO Box 4236, Chesterfield, MO 63006-4236. (636) 532-8228; Fax: (314) 995-4108. National Hydrocephalus Foundation. 12413 Centralia Road, Lakewood, CA 90715-1623. (888) 857-3434; Fax: (562) 924-6666. .

Scott J. Polzin, MS, CGC

Dawson disease see Subacute sclerosing parencephalitis de Morsier syndrome see Septo-optic dysplasia Deafness see Hearing disorders Decerebrate posturing see Abnormal body posture Decorticate posturing see Abnormal body posturing

Purpose DBS is used to treat Parkinson’s disease (PD) and essential tremor (ET). It has also been used to treat dystonia, chronic pain, and several other conditions The movement disorders of PD and ET are due to loss of regulation in complex circuits within the brain that control movement. While the cause of the two diseases differ, in both cases, certain parts of the brain become overactive. Surgical treatment can include destruction of part of the overactive portion, thus rebalancing the regulation within the circuit. It was discovered that the same effect could be obtained by electrically stimulating the same areas, which is presumed to shut down the cells without killing them. DBS may be appropriate for patients with PD or ET whose symptoms are not adequately controlled by medications. In PD, this may occur after five to ten years of successful treatment. Continued disease progression leads to decreased effectiveness of the main treatment for PD, levodopa. Increasing doses are needed to control symptoms, and over time, this leads to development of unwanted movements, or dyskinesias. Successful DBS allows a reduction in levodopa, diminishing dyskinesias. For PD, deep brain stimulation is performed on either the globus pallidus internus (GPi) or the subthalamic nucleus (STN). Treatment of essential tremor usually targets the thalamus. Each of these brain regions has two halves, which control movement on the opposite side of the body: right controls left, and left controls right. Unilateral (onesided) DBS may be used if the symptoms are much more severe on one side. Bilateral DBS is used to treat symptoms on both sides.

Precautions DBS is major brain surgery. Bleeding is a risk, and patients with bleeding disorders or who are taking blood thinning agents may require special management. DBS leaves metal electrodes implanted in the head, and patients are advised not to undergo diathermy (tissue heating) due to the risk of severe complications or death. Diathermy is used to treat chronic pain and other conditions. Special cautions are required for patients undergoing MRI after implantation.

❙ Deep brain stimulation Definition

In deep brain stimulation (DBS), electrodes are implanted within the brain to deliver a continuous low electric current to the target area. The current is passed to the electrodes through a wire running under the scalp and skin to a battery-powered pulse generator implanted in the chest wall.

Description In DBS, a long thin electrode is planted deep within the brain, through a hole in the top of the skull. To make sure the electrode is planted in the proper location, a rigid “stereotactic frame” is attached to the patient’s head before surgery. This device provides a three-dimensional coordinate system, used to locate the target tissue and to track the placing of the electrodes.

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Klein, O., et al. “Dandy-Walker Malformation: Prenatal Diagnosis and Prognosis.” Childs Nervous System 19 (August 2003): 484–9. Koble, Nicole, et al. “Dandy-Walker Malformation: Prenatal Diagnosis and Outcome.” Prenatal Diagnosis20 (2000): 318–327.

Delirium

A single “burr hole” is made in the top of the skull for a unilateral procedure. Two holes are made for a bilateral procedure. This requires a topical anesthetic. General anesthesia is not used, for two reasons. First, the brain does not feel any pain. Second, the patient must be awake and responsive in order to respond to the neurosurgical team as they monitor the placement of the electrode. The target structures are close to several nerve tracts that carry information throughout the brain. Abnormalities in vision, speech, or other cognitive areas may indicate that the electrode is too close to one of these regions, and thus needs repositioning. Other procedures may be used to ensure precise placement of the electrode, including electrical recording and injection of a contrast dye into the spinal fluid. The electrical recording can cause some minor odd sensations, but is harmless. The electrode is connected by a wire to an implanted pulse generator. This wire is placed under the scalp and skin. A small incision is made in the area of the collarbone, and the pulse generator is placed there. This portion of the procedure is performed under general anesthesia.

more so after surgery. Electrodes can be placed too close to other brain regions, which can lead to visual defects, speech problems, and other complications. If these occur, they may be partially reduced by adjusting the stimulation settings. DBS leaves significant hardware in place under the skin, which can malfunction or break, requiring removal or replacement.

Normal results Deep brain stimulation improves the movement symptoms of PD by 25–75%, depending on how carefully the electrodes are placed in the optimal target area, and how effectively the settings can be adjusted. These improvements are seen most while off levodopa; DBS does little to improve the best response to levodopa treatment. DBS does allow a reduction in levodopa dose, which usually reduces dyskinesias by 50% or more. This is especially true for DBS of the STN; DBS of the GPi may lead to a smaller reduction. Levodopa dose will likely be reduced, leading to a significant reduction in dyskinesias. DBS in essential tremor may reduce tremor in the side opposite the electrode by up to 80%. Resources

Preparation

BOOKS

A variety of medical tests are needed before the day of surgery to properly locate the target (GPi, thalamus, or STN), and fit the frame. These may include CT scans, MRI, and injection of dyes into the spinal fluid or ventricles of the brain. The frame is attached to the head on the day of surgery, which may be somewhat painful, although the pain is lessened by local anesthetic. A mild sedative is given to ease anxiety.

Aftercare Implantation of the electrodes, wire, and pulse generator is a lengthy procedure, and the patient will require a short hospital stay afterward to recovery from the surgery. Following this, the patient will meet several times with the neurologist to adjust the stimulator settings, in order to get maximum symptomatic improvement. The batteries in the pulse generator must be replaced every three to five years. This is done with a small incision as an outpatient procedure. The patient’s medications are adjusted after surgery. Most PD patients will need less levodopa after surgery, especially those who receive DBS of the STN.

Risks Risks from DBS include the surgical risks or hemorrhage and infection, as well as the risks of general anesthesia. Patients who are cognitively impaired may become 262

Jahanshahi, M., and C. D. Marsden. Parkinson’s Disease: A Self-Help Guide. New York: Demos Medical Press, 2000. WEBSITES

National Parkinson’s Disease Foundation. (December 4, 2003). . WE MOVE. (December 4, 2003). . ORGANIZATIONS

International Essential Tremor Foundation. P.O. Box 14005, Lenexa, Kansas 66285-4005. 913-341-3880 or 888-3873667; Fax: 913-341-1296. [email protected]. .

Richard Robinson

❙ Delirium Definition

Delirium is a transient, abrupt, usually reversible syndrome characterized by a disturbance that impairs consciousness, cognition (ability to think), and perception.

Description The word delirium is derived from the Latin delirare which literally translates “to go out of the furrow.” Delirium is typically an acute change in thinking with a disturbance in consciousness. Delirium is not a disease, but a syndrome that can occur as a result of many different

GALE ENCYCLOPEDIA OF NEUROLOGICAL DISORDERS

Demographics Patients who develop delirium during hospitalization have a mortality rate of 22–76% and a high death rate months after discharge. Approximately 80% of patients develop delirium near death, and 40% of patients in the intensive care units have symptoms of delirium. The prevalence of postoperative delirium following general surgery is 5–10%, and 42% following orthopedic surgery. Delirium is very common in nursing homes. The exact incidence of delirium in emergency departments is unknown. Delirium is present in approximately 20% of medical patients at the time of hospital admission. The prevalence in hospitalized patients is approximately 10% on a general medical service, 8–12% on a psychiatric service, 35–80% on a geriatric unit, and 40% on a neurologic service. In the elderly and postoperative patients, delirium may result in long-term disability, increased complications, and prolonged hospital stay. Geriatric patients have the highest risk for developing delirium. The incidence is higher among young children, females, and Caucasians. Medications are the most common cause of delirium in the elderly, which accounts for 22–39% of cases. Medications are the most common reversible causes of delirium. Approximately 25% of hospitalized patients with cancer and 30–40% of patients with HIV (AIDS) infection develop delirium during hospitalizations.

Abnormal mechanisms causing delirium There are three types of delirium based on the state of arousal. They include hyperactive delirium, hypoactive delirium, and mixed delirium. The hyperactive delirium is associated with drug intake such as alcohol withdrawal (or intoxication), amphetamine, phencyclidine (PCP), and lysergic acid diethylamide (LSD), a psychedelic compound. Hypoactive delirium is observed in patients with hypercapnia and hepatic encephalopathy. Patients who exhibit mixed delirium often exhibit nocturnal agitation, behavioral problems, and daytime sedation. The exact pathophysiological mechanisms that elicit delirium are not fully understood. Research that primarily studied subjects with alcohol withdrawal and hepatic encephalopathy indicated that delirium is caused by a reversible impairment of cerebral oxidative metabolism and multiple neurotransmitter abnormalities.

Key Terms Central nervous system (CNS) Contains the brain and spinal cord. Cerebral oxidative metabolism Using oxygen to generate energy by complex chemical reactions that occur in brain cells. Dementia A disorder characterized by loss of intellectual abilities; impairments in judgment, abstract thinking, and memory; and personality changes. Hepatic encephalopathy A change in mental state due to toxic substance buildup in the blood that is caused by liver failure. Hypercapnia Excess carbon dioxide in the blood. Hypoglycemia blood.

Low levels of glucose in the

Interleukins Chemicals released in the body as a result of stress to the body.

Neurotransmitter abnormality Acetylcholine is an excitatory chemical in the central nervous system (CNS). Anticholinergic medications, which disrupt release of acetylcholine, typically cause acute confusional states (delirium). Additionally, patients with diseases such as Alzheimer’s disease with impaired cholinergic transmission and decreased acetylcholine are susceptible to delirium. Patients who develop postoperative delirium have an increase in serum anticholinergic activity. Another neurotransmitter in the brain called dopamine causes delirium if there is an excess of dopaminergic activity. Dopaminergic and cholinergic activity in the brain exhibit a reciprocal relationship (i.e., a decrease in cholinergic activity leads to delirium, while an increase in dopaminergic activity leads to delirium). Studies have demonstrated that serotonin levels are increased in patients with septic delirium and encephalopathy. Serotoninergic agents, which are medications that may have unwanted side effects, leading to impaired serotonin release, can also cause delirium. Gama-aminobutyric acid (GABA) is an inhibitory neurochemical in the central nervous system. GABA is increased in patients with hepatic encephalopathy; this is probably caused by increases in ammonia levels.

Inflammatory mechanisms Recent research indicates that there is a role for specific chemical mediators such as interleukin-1 (IL-1) and interleukin-6 (IL-6). These chemical mediators are

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underlying conditions. Typically, there is a broad range of accompanying symptoms. Delirium is also called acute confusional state. Delirium is a medical emergency and affects 10–30% of hospitalized patients with medical illness. It is a widespread condition that affects more than 50% of persons in certain high-risk population. Often the condition can be reversed, but delirium is associated with increased morbidity and mortality rates.

Delirium

released from cells after a broad range of infectious and toxic insults. Head trauma and ischemia, which are frequently associated with delirium, cause brain responses that are mediated by IL-1 and IL-6. Abnormal release can cause damage to nerve cells.

Structural mechanisms Specific objective nerve pathways in the brain that induce delirium are unknown. Neuroimaging studies in patients with traumatic brain injury (TBI), stroke, and hepatic encephalopathy indicate that certain anatomical nerve pathways may contribute to a delirious state more than others. A specific pathway called the dorsal tegmental is also involved in delirium.

Summary of causes In general, the causes of delirium fall within 11 categories: infectious, withdrawal, acute metabolic, trauma, CNS disease, hypoxic, deficiencies, environmental, acute vascular, toxins/drugs, and heavy metals. Examples of diseases or disorders in each category include: • infectious: sepsis (infections that spread in blood and cause infections in the brain), encephalitis, meningitis, syphilis, CNS abscess • withdrawal: as a result of drug withdrawal from alcohol or sedatives • acute metabolic: acidosis, electrolyte disturbance, liver and kidney failure, other metabolic disturbances (glucose, Mg++, Ca++, conditions that affect the body’s regulation of acid and electrolyte balance) • trauma: head trauma, burns (delirium can occur secondary to traumatic events or severe burns) • CNS disease such as stroke, bleeding in the brain, or seizures • hypoxia: as a result of hypoxia (lack of oxygen), chronic obstructive lung disease (e.g., emphysema, bronchitis), or low blood pressure • deficiencies of vitamins, especially B-complex vitamins • environmental: severe changes in body temperature, either a decrease (hypothermia) or an increase (hyperthermia); hormonal imbalance (diabetes and thyroid problems) • acute vascular: conditions affecting blood vessels in the brain, such as hemorrhage or blockage of a blood vessel from a clot • toxins/drugs: chemical toxins such as street drugs, alcohol, pesticides, industrial poisons, carbon monoxide, cyanide, and solvents • heavy metals: exposure to certain metals such as lead or mercury 264

Other common causes of delirium include hypoglycemia and hyperthermia.

Diagnostic criteria for delirium The diagnosis of delirium is clinical, requiring physical examination and the analysis of symptoms because there is no single test that can successfully measure this condition. A careful history is essential to establish the diagnosis. Delirium is clinically characterized by an acutely transient alteration in mental status. Patients can have problems in orientation and short-term memory, difficulty sustaining attention, poor insight, and impaired judgment. In the hyperactive subtype of delirium, patients have an increased state of arousal, hypervigilance, and psychomotor abnormalities. Conversely, patients with the hypoactive subtype are typically withdrawn, less active, and sleepy. The mixed subtype category often presents with delirium as the primary symptom of an underlying illness. Mental status can be checked quickly and should include assessment of memory, attention, concentration, orientation, constructional tasks, spatial discrimination, writing, and arithmetic ability. Two of the most sensitive indicators for delirium are dysgraphia (impaired writing ability) and dysnomia (inability to name objects correctly).

Psychological deficit The psychological diagnostic criteria for delirium include: • change in cognition (i.e., disorientation, language disturbance, perceptual disturbance): this alteration cannot be accounted for by a preexisting, established, or evolving dementia • disturbance of consciousness (i.e., reduced clarity of awareness of the environment) occurs with a reduction in ability to focus, maintain, or shift (change) attention • the alterations develop over a short period (hours to days) and exhibit fluctuation during the day • evidence exists from history, medical and/or laboratory findings, which indicates that the delirium is caused by a general medical condition, substance intoxication, substance withdrawal, medication use, or more than one cause (multiple etiologies)

Diagnostic instruments There are several instruments that help establish the diagnosis of delirium. They include the Confusion Assessment Method (CAM), the Delirium Symptom Interview (DSI), and the Folstein Mini-Mental State Examination (MMSE). Delirium symptom severity can be assessed utilizing the Memorial Delirium Assessment Scale (MDAS) and the Delirium Rating Scale (DRS).

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Glucose levels can help diagnose delirium causes by hypoglycemia or uncontrolled diabetes. A complete blood count with differential cell analysis can help to diagnose infection and anemia. Electrolyte analysis can diagnose high or low levels. Renal (kidney) and liver function test (LFTs) can diagnose liver and/or kidney failure. Other tests that can assist with identifying the underlying cause of delirium include urine analysis (urinary tract infections), urine/blood drug screen (to diagnose the presence of toxic substance), thyroid function tests (to diagnose an underfunctioning thyroid gland, a condition called hypothyroidism), and special tests to diagnose bacterial and viral causes of infection. Neuroimaging studies such as computerized axial tomography (CAT) and magnetic resonance imaging (MRI) can be helpful to establish a diagnosis due to structural lesions or hemorrhage. Electroencephalogram (EEG), a special test that records brain activity in waves can be helpful to establish a diagnosis, especially in patients with hepatic encephalopathy (diffuse slow waves) and alcohol/sedative withdrawal (faster wave pattern).

Treatment Clinicians must be vigilant to aggressively identify the underlying etiology of delirium, since the condition is a medical emergency. Symptomatic treatment for delirium may include the use of antipsychotic drugs. These medications help to control hallucinations, agitation, and help to improve the level of orientation and attention abilities (sensorium). Haloperidol (Haldol) is a highly researched medication and is often administered in the symptomatic management of delirium. The typical dose for patients with delirium of moderate severity is 1–2 mg twice daily and repeated every four hours as needed. Haldol can be administered orally, intravenously, or by intramuscular injection. Elderly patients should start with lower doses of Haldol, typically 0.25–1.0 mg twice daily and repeated every four hours as needed.

Environmental interventions Treatment of delirium can be worsened by over stimulation or under stimulation in the environment. It is important to provide support and orientation to the patient. Additionally, providing the patients an environment with few distractions such as removing unnecessary objects in the room, use of clear language when talking to them, and avoidance of sensory extremes can be conducive to treatment planning.

Clinical trials Information concerning clinical trials and research on delirium can be obtained from the National Institutes of Health (NIH). Research related to delirium is active at the

Mayo Clinic Foundation, including research on Alzhiemer’s disease, postoperative delirium in orthopedic surgical patients, and pharmacological treatment of Parkinson’s disease. Resources BOOKS

Marx, John A., et al. (eds). Rosen’s Emergency Medicine: Concepts and Clinical Practice, 5th ed. St. Louis: Mosby, Inc., 2002. PERIODICALS

Chan, D., and N. Brennan. “Delirium: Making the Diagnosis, Improving the Prognosis.” Geriatrics 54, no. 3 (March 1999). Francis, J. “Three Millennia of Delirium Research: Moving Beyond Echoes of the Past.” Journal of the American Geriatrics Society 47, no. 11 (1999). Gleason, O. “Delirium.” American Family Physician (March 2003). Samuels, S., and M. M. Evers. “Delirium: Pragmatic Guidance for Managing a Common, Confounding, and Sometimes Lethal Condition.” Geriatrics 57, no. 6 (June 2002). WEBSITES

Delirium. (May 20, 2004) . National Cancer Institute. (May 20, 2004) . Association of Cancer Online Resources. (May 20, 2004) . ORGANIZATIONS

National Institute of Neurological Disorders and Stroke (NINDS) Neurological Institute. P.O. Box 5801, Bethesda, MD 20824.

Laith Farid Gulli, MD Nicole Mallory, MS, PA-C Robert Ramirez, DO

Dementia with Lewy bodies see Lewy body dementia Dementia, subcortical see Binswanger disease, Dementia

❙ Dementia Definition

The term dementia refers to symptoms, including changes in memory, personality, and behavior, that result from a change in the functioning of the brain. These declining changes are severe enough to impair the ability of a person to perform a function or to interact socially. This operating definition encompasses 70–80 different types of

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Lab studies

Dementia

dementia. They include changes due to diseases (Alzheimer’s and Creutzfeld-Jakob diseases), changes due to a heart attack or repeated blows to the head (as suffered by boxers), and damage due to long-term alcohol abuse. Dementia is not the same thing as delirium or mental retardation. Delirium is typically a brief state of mental confusion often associated with hallucinations. Mental retardation is a condition that usually dates from childhood and is characterized by impaired intellectual ability; mentally retarded individuals typically have IQ (intelligence quotient) scores below 70 or 75.

Description The absent-mindedness and confusion about familiar settings and tasks that are hallmarks of dementia used to be considered as part of a typical aging pattern in the elderly. Indeed, dementia historically has been called senility. Dementia is now recognized not to be a normal part of aging. The symptoms of dementia can result from different causes. Some of the changes to the brain that cause dementia are treatable and can be reversed, while other changes are irreversible.

Demographics An estimated two million people in the United States alone have severe dementia. Up to five million more people in the United States have milder forms of cognitive impairment of the dementia type. The elderly are most prone to dementia, particularly those at risk for a stroke. The historical tendency of women to live longer than men has produced a higher prevalence of dementia in older women. However, women and men are equally prone to dementia. Over age 80, more than 20% of people have at least a mild form of dementia.

Causes and symptoms Dementia is especially prominent in older people. The three main irreversible causes are Alzheimer’s disease, dementia with Lewy bodies, and multi-infarct dementia (also called vascular dementia). Degenerative forms of dementia are long lasting (chronic) and typically involve a progressive loss of brain cell function. In disorders like Alzheimer’s and CreutzfeldJakob diseases, this can involve the presence of infectious agents that disturb the structure of proteins that are vital for cell function. Other forms of dementia are chemically based. For example, Parkinson’s disease involves the progressive loss of the ability to produce the neurotransmitter dopamine. Interrupted transmission of nerve impulses causes the progressive physical and mental deterioration. Huntington’s disease is an inherited form of dementia that occurs when neurons (brain cells) degenerate. 266

Key Terms Amyloid plaques A waxy protein substance that forms clumps in brain tissues, leading to brain cell death as in Alzheimer disease. Lewy bodies Spheres, found in the bodies of dying cells, that are considered to be a marker for Parkinson’s disease. Multi-infarct dementia Deterioration in mental function caused by numerous areas in the brain where narrowing of blood vessels has resulted in atherosclerotic plaque formation and damage to brain cells.

Alzheimer’s disease is the most common cause of dementia. The progressive death of nerve cells in the brain is associated with the formation of clumps (amyloid plaques) and tangles of protein (neurofibrillary tangles) in the brain. The loss of brain cells with time is reflected in the symptoms; minor problems with memory become worse, and impairment in normal function can develop. Alzheimer’s patients also have a lower level of a chemical that relays nerve impulses between nerve cells. As the brain damage progresses, other complications can ensue from the damage and these can prove fatal. Put another way, people die with Alzheimer’s, not from it. Dementia resulting from the abnormal formation of protein in the brain (Lewy bodies) is the second most common form of dementia in the elderly. It is unclear whether these structures are related to the brain abnormalities noted in Alzheimer’s patients. Lewy body formation differs from Alzheimer’s in that the speed of brain functions is affected more so than memory. In multi-infarct dementia, blood clots can dislodge and impede the flow of blood in blood vessels in the brain. The restricted flow of blood can lead to death of brain cells and a stroke. Dementias that are caused by the blockage of blood vessels are generally known as vascular dementia. This type of dementia can sometimes be reversed if the bloodvessel blockage can be alleviated. In contrast, the dementia associated with Alzheimer’s disease is non-reversible. Less common causes of dementia include Binwanger’s disease (another vascular type of dementia), Parkinson’s disease, Pick’s disease, Huntington’s disease, Creutzfeldt-Jakob disease, and acquired immunodeficiency syndrome (AIDS). A study published in 2002 documented a link between elevated levels of an amino acid called homocysteine in the blood and the risk of developing dementia,

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Symptoms of dementia include repeatedly asking the same question; loss of familiarity with surroundings; increasing difficulty in following directions; difficulty in keeping track of time, people, and locations; loss of memory; changes in personality or emotion; and neglect of personal care. Not everyone displays all symptoms. Indeed, symptoms vary based on the cause of the dementia. Also, symptoms can progress at different rates in different people.

Diagnosis Diagnosis of dementia typically involves a medical examination, testing of mental responses (such as memory, problem solving, and counting), and knowledge of the patient’s medical history (e.g., prescription and non-prescription drug use, nutrition, results of a physical examination, and medical history). Testing of the composition of the blood and urine can be helpful in ruling out specific causes such as thyroid disease or a deficiency in vitamin B12. Some blood tests can help alert clinicians to the possibility of dementia. For example, persons infected with the human immunodeficiency virus (HIV) have distinct proteins in their blood that are often associated with the presence of dementia. Visual examination of the brain can reveal structural abnormalities associated with dementia. Tests that are typically performed are computerized tomography (CT), magnetic resonance imaging (MRI), and positron emission tomography (PET). While accurate, such tests are not commonplace, and are rarely encountered outside of the research setting. Neuroimaging (CT or MRI scans) can be useful in excluding the possibility that dementia has resulted from an occlusion of a blood vessel, as in a stroke or due to the presence of a tumor.

Treatment team Family physicians, medical specialists such as neurologists and psychiatrists, physical therapists, counselors, personal caregivers, and family members can all be part of the treatment team for someone afflicted with dementia.

smoking. Medicines such as antidepressants, antipsychotics, and anxiolytics can also be used to treat behaviors associated with dementia, including insomnia, anxiety, depression, and nervousness. Other treatments that do not involve drugs are the maintenance of a healthy diet, regular exercise, stimulating activities and social contacts, and making the home as safe as possible. Hobbies can help keep the mind occupied and stimulated. “Things-to-do” lists can be a helpful memory prompt for persons with early dementia. With more advanced disease, a facility specializing in Alzheimer’s treatment often provides a stimulating modified environment along with meeting increasing medical and personal care needs.

Recovery and rehabilitation Irreversible causes of dementia reduce or eliminate the chances of recovery and rehabilitation. Stimuli such as favorite family photographs and calendars provide clues to cognitive orientation, while devices such as walkers help maintain mobility for as long as possible.

Clinical trials As of early 2004, there are 64 clinical trials for dementia study and treatment in the United States that are recruiting subjects. The trials range from improved strategies of care and telephone support to active interventions in the outcome of various forms of dementia. The bulk of the trials are concerned with Alzheimer’s disease. Information about the trials can be found at the National Institutes of Health (NIH) sponsored clinical trials website.

Prognosis For those with irreversible progressive dementia, the outlook often includes slow deterioration in mental and physical capacities. Eventually, help is often required when swallowing, walking, and even sitting become difficult. Aid can consist of preparing special diets that can be more easily consumed and making surroundings safe in case of falls. Lift assists in areas such as the bathroom can also be useful. For those with dementia, the expected lifespan is often reduced from that of a healthy person. For example, in Alzheimer’s disease, deterioration of areas of the brain that are vital for body functions can threaten survival.

Treatment Drugs can help delay the progression of symptoms, particularly for Alzheimer’s disease. The high blood pressure that is associated with multi-infarct dementia can also be controlled by drug therapy. Other stroke risk factors that can be treated include cholesterol level, diabetes, and

Special concerns Caring for an individual with dementia almost always challenges family resources. Licensed social service providers at hospitals and facilities for the elderly can provide information and referrals regarding support groups,

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likely vascular dementia. As homocysteine concentration can be modified by diet, the finding holds the potential that one risk factor for dementia may be controllable.

Depression

mental health agencies, community resources, and personal care providers to assist families in caring for a person with dementia. Resources BOOKS

Bird, T. D. “Memory Loss and Dementia.” In Harrison’s Principles of Internal Medicine, 15th edition. Edited by A. S. Franci, E. Daunwald, and K. J. Isrelbacher. New York: McGraw Hill, 2001. Castleman, Michael, et al. There’s Still a Person in There: The Complete Guide to Treating and Coping With Alzheimer’s. New York: Perigee Books, 2000. Mace, Nancy L., and Peter V. Rabins. The 36-Hour Day: A Family Guide to Caring for Persons with Alzheimer Disease, Related Dementing Illnesses, and Memory Loss in Later Life. New York: Warner Books, 2001. PERIODICALS

Sullivan, S. C., and K. C. Richards. “Special Section— Behavioral Symptoms of Dementia: Their Measurement and Intervention.” Aging and Mental Health (February 2004): 143–152. Seshadri, S., et al. “Plasma Homocysteine as a Risk Factor for Dementia and Alzheimer’s Disease.” New England Journal of Medicine (February 2002): 476–483. OTHER

Mayo Clinic. Dementia: It’s Not Always Alzheimer’s. December 23, 2003 (March 30, 2004). . National Institute on Aging. Forgetfulness: It’s Not Always What You Think. December 23, 2003 (March 30, 2004). . ORGANIZATIONS

Alzheimer’s Association. 919 Michigan Avenue, Suite 1100, Chicago, IL 60611-1676. (312) 335-8700 or (800) 2723900; Fax: (312) 335-1110. [email protected]. . Alzheimer’s Disease Education and Referral Center. P. O. Box 8250, Silver Spring, MD 20907-8250. (301) 495-3334 or (800) 438-4380. [email protected]. . National Institute on Aging. 31 Center Drive, MSC 2292, Building 31, Room 5C27, Bethesda, MD 20892. (301) 496-1752 or (800) 222-2225. [email protected]. . National Institute for Neurological Disorders and Stroke. P. O. Box 5801, Bethesda, MD 20824. (301) 496-5761 or (800) 352-9424. . National Institute of Mental Health. 6001 Executive Boulevard, Room 8184, MSC 9663, Bethesda, MD 20892-9663. (301) 443-4513 or (866) 615-6464; Fax: (301) 443-4279. [email protected]. .

Brian Douglas Hoyle, PhD 268

❙ Depression Definition

When discussing depression as a symptom, a feeling of hopelessness is the most often described sensation. Depression is a common psychiatric disorder in the modern world and a growing cause of concern for health agencies worldwide due to the high social and economic costs involved. Symptoms of depression, like the disorder itself, vary in degree of severity, and contribute to mild to severe mood disturbances. Mood disturbances may range from a sudden transitory decrease in motivation and concentration to gloomy moods and irritation, or to severe, chronic prostration. With treatment, more than 80% of people with depression respond favorably to medications, and the feeling of hopelessness subsides. With treatment, most people are able to resume their normal work and social activities. Depression may occur at almost any stage of life, from childhood to middle or old age, as a result of a number of different factors that lead to chemical changes in the brain. Traumatic experiences, chronic stress, emotional loss, dysfunctional interpersonal relationships, social isolation, biological changes, aging, and inherited predisposition are common triggers for the symptoms of depression. Depression is classified according to the symptoms displayed and patterns of occurrence. Types of depression include major depressive disorder, bipolar depressive disorder, psychotic depressive disorder, postpartum depression, premenstrual dysphoric disorder, and seasonal disorder. Additional types of depression are included under the label of atypical depressive disorder. Many symptoms overlap among the types of depression, and not all people with depression experience all the symptoms associated with their particular type of the disorder.

Description Symptoms of a depressive disorder include at least five of the following changes in the individual’s previous characteristics: loss of motivation and inability to feel pleasure; deep chronic sadness or distress; changes in sleep patterns; lack of physical energy (apathy); feelings of hopelessness and worthlessness; difficulty with concentration; overeating or loss of appetite; withdrawal from interpersonal interactions or avoidance of others; death wishes, or belief in his/her own premature death. In children, the first signs of depression may be irritation and loss of concentration, apathy and distractibility during classes, and social withdrawal. Some adults initially complain of constant fatigue, even after long hours of sleep, digestive disorders, headaches, anxiety, recurrent memory lapses, and insomnia or excessive sleeping. An episode of major

GALE ENCYCLOPEDIA OF NEUROLOGICAL DISORDERS

Anorexia Loss of appetite. Bipolar disorder A mood disorder characterized by periods of excitability (mania) alternating with periods of depression. Dysthymia A chronic mood disorder characterized by mild depression. Major depressive disorder A mood disorder characterized by overwhelming and persistent feelings of hopelessness, often accompanied by sleep disturbances, withdrawal from normal social and personal care activities, and an inability to concentrate. Manic A period of excess mental activity, often accompanied by elevated mood and disorganized behavior. Serotonin A type of neurotransmitter, a brain chemical that carries messages between brain cells. Low levels of serotonin in the brain are associated with feelings of depression.

depression may be preceded by a period of dysthymia, a mild but persistent low mood state, usually accompanied by diminished sexual drive, decreased affective response, and loss of interest in normal social activities and hobbies. Most individuals with depression have difficulty in dealing with the challenges of daily life, and even minor obstacles or difficulties may trigger exaggerated emotional responses. Frustrating situations are frequently met with feelings of despair, dejection, resentment, and worthlessness, with people easily desisting from their goals. People with depression may try to avoid social situations and interpersonal interactions. Some people with depression overeat, while others show a sharp loss of appetite (anorexia). In some individuals, medical treatments for some other existing illness may also cause depression as an adverse reaction. For instance, antihypertensive drugs, steroids, muscle relaxants, anticancer drugs, and opioids, as well as extensive surgery such as a coronary bypass, may lead to depression. Cancer and other degenerative diseases, chronic painful conditions, metabolic diseases or hormonal changes during adolescence, or after childbirth, menopause, or old age may be potential triggers for depression. When the first onset of depression occurs after the age of 60, there is a greater possibility that the causative factor is a cerebrovascular (blood vessels in the brain) degeneration. Molecular genetics research has recently shown that mutations in a gene coding for a protein that transports

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Key Terms

serotonin (a neurotransmitter) to neurons may determine how an individual will cope with stressful situations. A two-decade study involving 847 people of both sexes has shown that those who inherited two copies of the long version of the gene 5-HTT have a 17% risk of suffering a major depressive episode due to exposure to four or more identified stressful situations in their lives, whereas those with one long and one short version of the gene had the risk increased to 33%. The study has also shown that individuals with two short copies of the gene have a 43% probability of a major depressive episode when exposed to four or more stressful life events. The shorter version of the gene 5-HTT does not directly causes depression, but offers less protection against the harmful effects of traumatic or stressful situations to the brain. Studies of population genetics have also shown that about 50% of the world’s Caucasian population carry one short and one long version of 5-HTT genes. Depressive episodes may be associated with additional psychiatric disorders. Neurotic depression is often triggered by one or more adverse life events or traumatic experiences that have historically caused anxiety in the life of the person experiencing depression. For example, loss of social or economical status, chronic failure in living up to the expectations of parents, teachers, or bosses, death of a close relation, work-related competitive pressures, and other stressful situations such as accidents, urban violence, wars, and catastrophic events may lead to a depressive episode. Conversely, anxiety disorders such as panic syndrome, phobias, generalized anxiety, and post-traumatic stress disorder may trigger a major depressive crisis. Psychotic depressive disorders are likely to be associated with other psychiatric diseases or caused by them. Eating disorders such as bulimia, anorexia nervosa, and binge-eating disorder are generally accompanied by depression or may be caused by an existing depressive state. Neurodegenerative diseases such as Alzheimer’s, Huntington’s, and Parkinson’s diseases frequently have depression among their symptoms. Dysthymia is a mild but chronic depressed state, characterized by melancholic moods, low motivation, poor affective responsiveness, and a tendency for self isolation. A dysthymic state lasting two years or longer is a risk factor for the onset of a major depressive episode. However, many dysthymic individuals experience a chronic low mood state throughout their daily lives. Dysthymia is a frequent occurrence in individuals involved in chronic dysfunctional marriages or unsatisfying work conditions. Such chronic stressful situations alter the brain’s neurochemistry, thus the opportunity arises for symptoms of depression to develop. Psychotic depression is a particularly serious illness and possesses biological and cognitive (thought) components. Psychotic depression involves disturbances in

Depression Colored positron emission tomography (PET) scans showing the brain of a depressed person (top) and the brain of a healthy person. (© Photo Researchers. Reproduced by permission.)

brain neurochemistry as a consequence of either a congenital (from birth) condition or due to prolonged exposure to stress or abuse during early childhood. Prolonged exposure to severe stress or abuse in the first decade of life induces both neurochemical and structural permanent changes in the developing brain with a direct impact on emotional aspects of personality. Normal patterns of perception and reaction give way to flawed mechanisms in order for a person to cope with chronic fear, abuse, and danger. Perception becomes fear-oriented and conditioned to constantly scan the environment for danger, with the flight-or-fight impulse underlying the individual’s reactions. Delusions, misinterpretation of interpersonal signals, and a pervading feeling of worthlessness may impair the individual’s ability to deal with even minor frustrations or obstacles, precipitating deep and prolonged episodes of depression, often with a high risk of suicide. Hallucinations may also occur, such as hearing voices or experiencing visions, as part of depression with psychosis. 270

A major depressive disorder (MDD) or clinical depression may consist of a single episode of severe depression requiring treatment or constitute the initial sign of a more complex disorder such as bipolar disorder. MDD may last for several months or even years if untreated and is associated with a high risk of suicide. In bipolar disorder, manic (hyper-excited and busy) periods alternate with deep depressive episodes, and are characterized by abnormal euphoria (an exaggerated feeling of happiness and well-being) and reckless behavior, followed by deep distress and prostration, often requiring hospitalization. Major episodes of depression may last for one or more years if not treated, leading to a deep physical and emotional prostration. The person with major depression often moves very slowly and reports a sensation of heaviness in the arms and legs, with simple walking requiring an overwhelming effort. Personal hygiene is neglected and the person often desires to stay secluded or in bed for days or weeks. Suicidal thoughts may frequently occupy the mind or become recurrent patterns of thinking. Painful or unsettling memories are often recalled, and contribute to feelings of helplessness. Atypical depression causes a cyclic behavior, alternating periods of severe and mild depressive states, punctuated by mood swings, hypersensitivity, oversleeping, overeating, with or without intermittent panic attacks. This depressive disorder is more common in women, with the onset usually occurring during adolescence. Premenstrual dysphoric disorder (PDD) is not premenstrual stress. It is a more severe mood disorder that can cause deep depression or episodes of heightened irritation and aggressiveness, starting one or two weeks before menstruation and usually persisting during the entire period. Premenstrual dysphoric disorder is associated with abnormal changes in levels of hormones that affect brain neurochemistry. Seasonal affective disorder (SAD) is caused by disturbances in the circadian cycle, a mechanism that controls conversion of serotonin into melatonin in the evening and mid-afternoon, and the conversion of melatonin into serotonin during daytime. Serotonin is the neurotransmitter responsible for sensations of satiety and emotional stability, which is converted at nighttime into melatonin, the hormone that regulates sleep and other functions. Some people are especially susceptible to the decreased exposure to daylight during long winter months and become depressed and irritable. Overeating and oversleeping during the winter season are common signs of seasonal affective disorder, along with irritation and depressed moods. However, as the amount of light increases during the spring and summer seasons, the symptoms disappear. Postpartum depression is a severe and long-lasting depressive state also associated with abnormal changes in

GALE ENCYCLOPEDIA OF NEUROLOGICAL DISORDERS

Without treatment, the risk of suicide as a consequence of depression should not be underestimated. Suicide accounts for approximately 15% of deaths among people with significant depression, and half of all suicide attempts in the United States are associated with depression. Persistent and recurrent depressive episodes are important contributors to other diseases alike such as myocardial infarction, hypertension, and other cardiovascular disorders. Resources BOOKS

Klein, Donald F., MD. Understanding Depression: A Complete Guide to Its Diagnosis and Treatment. New York: Oxford Press, 1995. Solomon, Andrew. The Noonday Demon: An Atlas of Depression. New York: Scribners, 2002.

Description Dermatomyositis is characterized by the onset of symptoms that can be severe, with rash and muscle weakness occurring over a large portion of the body. The term dermatomyositis stems from the root word “derm,” referring to the skin, and the word “myositis,” which means inflammation of muscles. Dermatomyositis, therefore, means an inflammation of the muscles and the skin. The disease was first described in 1887 in Germany.

Demographics Both children and adults can be affected with dermatomyositis, but females are twice as likely to have the disorder as males. One-third of the cases occur in people over the age of 50. People of European ancestry have typically been more affected than people of African ancestry. As of 2004, however, the incidence of dermatomyositis is rising faster in African Americans than in whites. In the United States, the estimated prevalence of the disease is 5.5 cases per million people.

Causes and symptoms

PERIODICALS

Manji, H. K., W. C. Drevets, and D. S. Charney. “The Cellular Neurobiology of Depression.” Nature Medicine (May 2001) 7: 541–546. Teicher, Martin H. “Wounds That Won’t Heal—The Neurobiology of Child Abuse.” Scientific American (March 2002): 68–75. OTHER

National Institute of Mental Health. Depression. February 12, 2004 (March 31, 2004). . ORGANIZATIONS

National Institute of Mental Health (NIMH). Office of Communications, 6001 Executive Boulevard, Room 8184, MSC 9663, Bethesda, MD 20892-9663. (301) 4434513 or (800) 615-NIMH (6464); Fax: (301) 443-4279. [email protected]. .

Sandra Galeotti

❙ Dermatomyositis Definition

Dermatomyositis is one member of a group of diseases that are collectively called inflammatory myopathies. A myopathy is a disorder of a muscle. Hallmarks of dermatomyositis disease are a widespread rash and muscle weakness.

The cause of dermatomyositis is a disruption in the functioning of the immune system, although the precise details of the malfunction are not yet known. While the basis of the disease may be due to a genetic mutation, conclusive evidence is lacking. Infection with certain viruses, or a bacterium called Borrelia (the cause of Lyme disease), has been suggested as possible triggers of the disease. Dermatomyositis is often first apparent as a rash. The rash, which can be bluish-purple in color, reminiscent of bruising, typically occurs in patches on the face, neck, shoulders, upper portion of the chest, elbows, knuckles, knees, and back. Sometimes there can be accumulation of calcium as hard bumps underneath the skin in the region of the rash. The skin may break open and become very itchy, to the point of disturbing sleep. The other principle symptom, which usually appears after the rash, but which can also be coincident with the rash, is muscle weakness. The muscles most often affected are those that are near the central part of the body, such as muscles of the chest and the upper arms and legs. As the disease progresses, muscles toward the outer parts of the arms and legs can weaken. As well, the affected muscles can become sore and painful to the touch. The muscle weakness can make it hard for the affected person to get up from a sitting position, climb up stairs, lift even moderately heavy objects, and to reach up over their head. Swallowing can become difficult. People may also feel tired, lose weight, and develop a slight fever. Except for the presence of rash, the symptoms of dermatomyositis are virtually the same as a related disease

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hormone levels affecting brain neurochemistry. If untreated, postpartum depression may last for months or even years, and is highly disruptive to family and maternal-child relations.

Dermatomyositis

Recovery and rehabilitation

Key Terms Glucocorticoid medications A group of medications that produces effects of the body’s own cortisone and cortisol. Glucocorticoids are commonly called steroids and, among other functions, work to reduce inflammation. Myositis Inflammation of a muscle.

known as polymyositis (inflammation of many muscles). In about 40% of those with dermatomyositis, only the skin is affected. In these people, the disease can also be called amyopathic dermatomyositis (ADM), or DM sine myositis.

Diagnosis Diagnosis is based on the presence of skin rash, muscle weakness, and higher than normal levels of some muscle enzymes (due to breakdown of muscle cells). A muscle biopsy, in which a sample of muscle is obtained, can reveal inflammation and the death of muscles cells associated with the weakening muscle. Because of the presence of cancer in a significant proportion of elderly people who develop the disease, diagnosis is often accompanied by procedures like a chest x ray, mammogram in women, prostate examination in men, and sometimes a scan of the abdomen using the technique of computed tomography.

Treatment team The treatment team for a case of dermatomyositis is typically made up of the family physician, neurologist, physical therapists, and family members or caregivers. Sometimes the team also includes a dermatologist (specialist in the structure, functions, and diseases of the skin) and a rheumatologist (specialist in conditions that cause swelling or pain in the muscles and joints).

Treatment Treatment principally consists of therapy with glucocorticoid medications, which help quell an immune response that can exacerbate the rash. The steroid that is typically given is prednisone. In some people, this drug is not effective or tolerated well. Alternate drugs that can be given are azathioprine and methotrexate. An immune compound called immunoglobulin can also be given intravenously. 272

Physical therapy is often used to try to maintain or minimize the loss of muscle strength and function. As dermatomyositis is a chronic condition, emphasis is placed not on recovery, but on maintaining optimum muscle function.

Clinical trials As of April 2004, there are seven clinical trials related to dermatomyositis or other related conditions recruiting participants in the United States. Some of the trials are evaluating new treatments such as novel drugs and irradiation. Other trials are trying to uncover how the disorder develops in children. Updated information about ongoing trials can be found at the National Institutes of Health website for clinical trials at . As well as the clinical trials, research is being undertaken to unravel the mechanisms of development of the disease, with a goal to prevent, treat, and ultimately, cure dermatomyositis.

Prognosis The disease is seldom fatal, although muscle weakness can persist for life. Most cases of dermatomyositis do respond to therapy, which improves a person’s outlook. However, the prognosis may not be as good if the disease is accompanied by heart or lung problems. In the latter cases, a person may become confined to a wheelchair. On rare occasions, heart or lung muscles weakened by dermatomyositis can cause death.

Special concerns Approximately one-third of older people who develop dermatomyositis also have cancer. In some cases, the cancer may not yet be diagnosed. Therefore, a thorough physical examination of all body systems is important after receiving a diagnosis of dermatomyositis. Resources BOOKS

Parker J. N., and P. M. Parker. The Official Parent’s Sourcebook on Dermatomyositis: A Revised and Updated Directory for the Internet Age. San Diego, Icon Group International, 2002. PERIODICALS

Grogan, P. M., and J. S. Katz. “Inflammatory Myopathies.” Current Treatment Options in Neurology (March 2004): 155–161. OTHER

Callen, J. P. “Dermatomyositis.” eMedicine. April 14, 2004 (May 27, 2004). .

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ORGANIZATIONS

American Autoimmune Related Diseases Association. 22100 Gratiot Avenue, Eastpointe, MI 48201-2227. (586) 7763900 or (800) 598-4668; Fax: (586) 776-3903. [email protected]. . Myositis Association. 1233 20th Street, NW, Washington, DC 20036. (202) 887-0084 or (800) 821-7356; Fax: (202) 466-8940. [email protected]. . National Institute for Neurological Diseases and Stroke (NINDS), 6001 Executive Boulevard, Bethesda, MD 20892. (301) 496-5751 or (800) 352-9424. . National Institute of Arthritis and Musculoskeletal and Skin Diseases (NIAMS). 31 Center Dr., Rm. 4C02 MSC 2350, Bethesda, MD 20892-2350. (301) 496-8190 or (877) 2264267. [email protected]. . National Organization for Rare Disorders. 55 Kenosia Avenue, Danbury, CT 06813-1968. (203) 744-0100 or (800) 9996673; Fax: (203) 798-2291. [email protected]. .

Key Terms Ataxia Loss of coordinated muscle movement caused by a disturbance of the nervous system. Myelin sheath Insulating layer around some nerves that speeds the conduction of nerve signals. Optic neuritis Inflammation of the optic nerve, often accompanied by vision loss. Transverse myelitis A neurologic syndrome caused by inflammation of the spinal cord.

patients that have multiple sclerosis usually appear after symptoms associated with Devic syndrome, distinguishing the two neurodegenerative diseases. Devic syndrome is also known as Devic disease and neuromyelitis optica. It is still controversial whether Devic syndrome is a variant of multiple sclerosis. It is considered by some scientists to be a variant of a disease caused by exposure to the varicella zoster virus that results in acute disseminated encephalomyelitis (ADEM).

Brian Douglas Hoyle, PhD

Demographics

Developmental dyspraxia see Dyspraxia

❙ Devic syndrome

Devic syndrome can occur spontaneously, or in conjunction with multiple sclerosis or systemic lupus erythematosus. It affects males and females equally. Devic syndrome is a rare disorder, affecting less than an estimated five persons per million population per year.

Definition

Devic Syndrome is a rare neurological disorder that affects both the protective sheet that lines the spinal cord and the optic nerve of the eye. People that have Devic syndrome lose the fatty covering of the spinal cord (myelin) and experience eye pain due to an exaggerated inflammatory response that occurs in the eye. The resulting spinal cord damage is known as transverse myelitis and the resulting eye inflammation is known as optic neuritis. Devic syndrome is a severe neurodegenerative disorder that can lead to blindness, paralysis, and incontinence (loss of bowel or bladder control).

Description Devic syndrome is an autoimmune disorder that is considered by many scientists to be a form of multiple sclerosis, another neurodegenerative disease that affects the protective coating of the spinal cord called the myelin sheath. In Devic syndrome, the course of the disease is more rapid and severe. Symptoms typically observed in

Causes and symptoms Devic syndrome is a chronic and degenerative disorder that usually affects both eyes. The eyes develop diminished sensitivity to bright lights, color vision impairment, and diminished light reflexes. Approximately two-thirds of persons with Devic syndrome experience complete visual loss. The symptoms begin with significant loss of vision that precedes muscle weakness, ataxia (coordination difficulties and unsteady gait, or manner of walking), and numbness. Inflammatory sites of attack are usually the optic nerve chiasma, optic tract, and spinal cord. Usually, the optic neuropathy (damage to the optic nerve) is accompanied by severe transverse myelitis, which involves an acute inflammation of the spinal cord. The optic neuropathy usually happens before the transverse myelitis occurs, but in approximately 20% of patients it occurs in the reverse order. Persons with Devic syndrome can also experience urinary, gastrointestinal, and sexual dysfunction. This occurs due to degeneration of the nerves that exit the spinal

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“NINDS Dermatomyositis Information Page.” National Institute of Neurological Disorders and Stroke. April 12, 2004 (May 27, 2004). .

Diabetic neuropathy disease

cord and serve the body’s trunk and limbs. Patients with Devic syndrome rarely experience clinical signs that involve defects beyond symptoms arising from the spinal cord and optic nerve. There are also characteristic brain MRI scan findings including swelling and signal changes that are typically observed, as well as increased protein content in the cerebral spinal fluid.

Diagnosis Diagnosis is usually made by a neurologist and an ophthalmologist, by examining the eye and initiating several neurological exams including an MRI of the brain.

Treatment team The neurologist and an ophthalmologist are the physicians that will be involved in making the diagnosis and providing follow-up treatment for persons with Devic syndrome. Patients that lose their eyesight will also require an occupational therapist that specializes in assisting individuals that become blind.

Treatment There is no cure available for Devic syndrome. Treatment, therefore, is based solely on lessening the symptoms and providing comfort care for individuals that are in the more advanced stages of the disease. Steroidal anti-inflammatory medications such as corticosteroids might be helpful and are commonly prescribed for patients with this disorder. There is no defined standard of treatment for the disorder.

Recovery and rehabilitation Recovery from attacks manifested by acute inflammation is often variable. Devic syndrome is a chronic disease, often progressive, and complete rehabilitation is usually not observed, as with many neurodegenerative diseases.

Clinical trials Currently, the National Institute of Neurological Disorder and Stroke (NINDS) at the National Institutes of Health (NIH) are investigating how to repair damage to the central nervous system while restoring full strength to injured areas. As of mid-2004, there is currently a Phase III clinical trial to determine the effectiveness of plasma exchange in the treatment of acute severe attacks of inflammatory demyelinating disease in patients with degenerative neurological disorders who do not respond to intravenous steroid therapy. Although the study is no longer recruiting participants, anticipated results are not yet published.

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Prognosis The prognosis for individuals that have Devic syndrome is poor, as the disorder is eventually fatal for many patients. Isolated acute demyelinated encephalomyelitis (ADE) affects the optic nerve and the spinal cord in a similarly to Devic syndrome, but occurs after an infection or a common cold, and is distinct from Devic syndrome. ADE patients can fully recover, although many have associated permanent deficits, and in rare cases ADE can also be fatal. Resources BOOKS

Johnson, Richard T., et. al., “Transverse Myelitis” in Current Therapy in Neurologic Disease, 6th. ed. New York: Elsevier, 2002. PERIODICALS

“Proposed diagnostic criteria and nosology of acute transverse myelitis,” Neurology 59, no. 4 (August 27, 2002): 499–505. OTHER

Lynn, Joann. “Transverse Myelitis: Symptoms, Causes and Diagnosis.” The Transverse Myelitis Association. (May 1, 2004). “NINDS Devic Syndrome Information Page.” National Institute of Neurological Disorders and Stroke. (May 2, 2004). Swallow, Charles T. “Optic neuritis.” eMedicine. March 26, 2002. (May 1, 2004). ORGANIZATIONS

Multiple Sclerosis Foundation. 6350 North Andrews Avenue, Ft. Lauderdale, FL 33309-2130. (954) 776-6805 or (888) MSFocus; Fax: (954) 351-0630. support@msfocus. org. . National Eye Institute (NEI), National Institutes of Health, DHHS. 31 Center Drive, Rm. 6A32 MSC 2510, Bethesda, MD 20892-2510. (301) 496-5248 or (800) 869-2020. [email protected]. . Transverse Myelitis Association. 3548 Tahoma Place West, Tacoma, WA 98466. (253) 565-8156. [email protected]. .

Bryan Richard Cobb, PhD

Dexamethasone see Glucocorticoids

❙ Diabetic neuropathy disease Definition

Diabetic neuropathy (DN) is a neurological disorder caused by consequences of a primary disease—diabetes mellitus. The diabetic neuropathy may be diffuse, affecting

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Autoimmune Pertaining to an immune response by the body against its own tissues or types of cells. Biopsy The surgical removal and microscopic examination of living tissue for diagnostic purposes or to follow the course of a disease. Most commonly the term refers to the collection and analysis of tissue from a suspected tumor to establish malignancy. Carpal tunnel syndrome A condition caused by compression of the median nerve in the carpal tunnel of the hand, characterized by pain. Diabetes mellitus The clinical name for common diabetes. It is a chronic disease characterized by the inability of the body to produce or respond properly to insulin, a hormone required by the body to convert glucose to energy. Electromyography (EMG) A diagnostic test that records the electrical activity of muscles. In the test, small electrodes are placed on or in the skin; the pat-

multiple parts of the body, or focal, targeting a specific nerve or body part.

Description Neurological damage is the result of chronically elevated blood sugar. Among all complications of diabetes, DN can be one of the most frustrating and debilitating conditions, because of the pain, discomfort, and disability it may cause, and because available treatments are limited and not always successful. There are three main types of DN: • Sensory neuropathy (or peripheral neuropathy, usually just referred to as neuropathy)—affects the nerves that carry sensation information to the brain, from various parts of the body, i.e.: how hot or cold something is, what the texture of something feels like, or the pain caused by a sharp object. This is the most common form of diabetic neuropathy. • Autonomic neuropathy—affects the nerves that control involuntary activities of the body, such as the action of the stomach, intestine, bladder, and even the heart. • Motor neuropathy—affects the nerves that carry signals from the brain to muscles, allowing all motions to occur, i.e. walking, moving the fingers, chewing. This form of neuropathy is very rare in diabetes.

terns of electrical activity are projected on a screen or over a loudspeaker. This procedure is used to test for muscle disorders, including muscular dystrophy. Gastroparesis Nerve damage of the stomach that delays or stops stomach emptying, resulting in nausea, vomiting, bloating, discomfort, and weight loss. Insulin A hormone or chemical produced by the pancreas that is needed by cells of the body in order to use glucose (sugar), a major source of energy for the human body. Ketoacidosis Usually caused by uncontrolled type I diabetes, when the body isn’t able to use glucose for energy. As an alternate source of energy, fat cells are broken down, producing ketones, toxic compounds that make the blood acidic. Symptoms of ketoacidosis include excessive thirst and urination, abdominal pain, vomiting, rapid breathing, extreme tiredness, and drowsiness.

The longer a person has diabetes, the more likely the development of one or more forms of neuropathy. Approximately 60–70% of patients with diabetes show signs of neuropathy, but only about five percent experience painful symptoms. According to the categories described above, DN can lead to muscular weakness, loss of feeling or sensation, and loss of autonomic functions such as digestion, erection, bladder control, sweating, and so forth.

Demographics In the United States, DN occurs in 10–20% of patients newly diagnosed with diabetes mellitus (DM), and its prevalence is up to 50% in elderly patients with DM. Most studies agree that the overall prevalence of symptomatic DN is approximately 30% of all patients with DM. The incidence of DN in the general population is approximately two percent. Internationally, DN is found in 20–30% of individuals with type-2 diabetes. This number depends on the fiber type being tested and the sensitivity of the exam. Individuals with type-1 diabetes usually develop neuropathy after more than ten years of living with the disease. It affects men and women equally, but neuropathic pain appears more frequently in females. Minority group members have more secondary complications, such as

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Key Terms

Diabetic neuropathy disease

lower extremity amputations. These individuals tend to also have more hospitalizations due to neuropathic complications.

Causes and symptoms Causes of diabetic neuropathy are likely to be different for different types of the disorder. Nerve damage is probably due to a combination of factors, such as: • Metabolic factors: high blood glucose, long disease duration, low levels of insulin and abnormal blood fat levels • Neurovascular factors, leading to blood vessel damage and consequent insufficient delivery of oxygen and nutrients to the nerves • Autoimmune factors, causing nerve inflammation • Mechanical nerve injury, such as carpal tunnel syndrome

• A comprehensive foot exam assesses skin, circulation, and sensation. Other tests include checking reflexes and assessing vibration perception. • Nerve conduction studies check the transmission of an electrical current through a nerve. This test allows the doctor to assess the condition of all the nerves in the arms and legs. • Electromyography (EMG) shows how well muscles respond to electrical signals transmitted by nearby nerves. This test is often done at the same time as nerve conduction studies. • Quantitative sensory testing (QST) uses the response to stimuli, such as pressure, vibration, and temperature, to check for overt neuropathy. QST is increasingly used to recognize sensation loss and excessive irritability of nerves

• Inherited traits that increase susceptibility to nerve disease

• Heart rate variability shows how the heart responds to deep breathing and to changes in blood pressure and posture.

• Lifestyle factors, such as smoking or alcohol use

• Nerve or skin biopsies are used in research settings

Symptoms depend on the neuropathy type and affected nerves. Some people show no symptoms at all. Often, symptoms are minor at first, and because most nerve damage occurs over several years, mild cases may go unnoticed for a long time. Symptoms may include: • Numbness, tingling, or pain in the toes, feet, legs, hands, arms, and fingers • Wasting of feet or hands muscles • Indigestion, nausea, or vomiting • Diarrhea or constipation • Dizziness or faintness due to a drop in postural blood pressure

Treatment team Proper management of diabetic patients requires a skilled team including collaborating specialists. Depending on the qualifications of the patient’s primary physician, other professionals are recruited as needed, such as an ophthalmologist, podiatrist, cardiologist, nutritionist, nurse educator, neurologist, vascular surgeon, endocrinologist, gastroenterologist and urologist. A nurse educator can ease the interface between otherwise independent specialists. Without such a team mentality, the diabetic patient is often set adrift, forced to cope with conflicting instructions and unneeded repetition of tests.

• Problems with urination

Treatment

• Erectile dysfunction (impotence) or vaginal dryness • Weakness In addition, weight loss and depression are not a direct consequence of the neuropathy but, nevertheless, often accompany it.

Diagnosis Diabetic neuropathy is diagnosed on the basis of a clinical evaluation, analyzing the patient’s history, symptoms and the physical exam. During the exam, the doctor may check blood pressure and heart rate, muscle strength, reflexes, and sensitivity to position, vibration, temperature, or a light touch. The physician may also do other tests to help determine the type and extent of nerve damage: 276

The first step is to bring blood glucose levels down to the normal range to prevent further nerve damage. Blood glucose monitoring, meal planning, exercise, and oral drugs or insulin injections are needed to control blood glucose levels. Although, symptoms may get temporarily worse when blood sugar is first brought under control, over time, maintaining normal glucose levels helps lessen neuropathic symptoms. Importantly, good blood glucose control may also help prevent or delay the onset of further complications. Additional treatments depend on the type of nerve problem in consideration, and are include: • Foot care—Clean the feet daily, using warm water and a mild soap. Inspect the feet and toes every day for cuts, blisters, redness, swelling, calluses, or other problems.

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Recovery and rehabilitation Physical therapy may be a useful adjunct to other therapies, especially when muscular pain and weakness are a manifestation of the patient’s neuropathy. The physical therapist can instruct the patient in a general exercise program to maintain his/her mobility and strength. Occupational therapy may be necessary in cases where a person loses a limb due to secondary complications and needs functional training to regain his/her independence.

Clinical trials There are numerous open clinical trials for diabetic neuropathy disease: • Gene Therapy to Improve Wound Healing in Patients With Diabetes, at the National Institute of Arthritis and Musculoskeletal and Skin Diseases (NIAMS) • Long-Term Treatment and Re-Treatment of Lower Extremity Diabetic Ulcers with Regranex or Placebo, sponsored by Johnson & Johnson Pharmaceutical Research and Development

• RhVEGF (Telbermin) for Induction of Healing of Chronic, Diabetic Foot Ulcers, sponsored by Genentech • Study of Three Fixed Doses of EAA-090 in Adult Outpatients with Neuropathic Pain Associated with Diabetic Neuropathy, sponsored by Wyeth-Ayerst Research • Treatment for Symptomatic Peripheral Neuropathy in Patients with Diabetes, LY333531 Treatment for Symptomatic Peripheral Neuropathy in Patients with Diabetes and Treatment of Peripheral Neuropathy in Patients with Diabetes, sponsored by Eli Lilly and Company • VEGF for Diabetic Neuropathy, at the Caritas St. Elizabeth’s Medical Center of Boston. For updated information on clinical trials, visit the website www.clinicaltrials.org, sponsored by the United States government.

Prognosis The mechanisms of diabetic neuropathy are poorly understood. At present, treatment alleviates pain and can control some associated symptoms, but the process is generally progressive. Complications of diabetic neuropathy may include: • Progression to cardiovascular autonomic neuropathy, a relatively rare occurrence which can eventually cause death • Peripheral neuropathy that leads to foot ulcers and leg amputations • Injuries associated with automonic neuropathy, including those from dizziness and falling • gastric distress leading to nausea and vomiting, diarrhea and dehydration, which could impair the ability to regulate blood sugar.

Special concerns Prevention of diabetic neuropathy can be achieved by establishing good control over blood sugar levels at the onset of diabetes. Even when symptoms of neuropathy are already present, maintaining normal blood sugar levels reduces pain significantly. Drugs such as some over-thecounter anti-inflamatories may aid in prevention, as well as deterrence, of neuropathy by keeping inflammation to a minimum. Resources BOOKS

Parker, James N., Phillip M. Parker. The Official Patient’s Sourcebook on Diabetic Neuropathy: A Revised and Updated Directory for the Internet Age. Icon Group, International, 2002.

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Always wear shoes or slippers to protect feet from injuries, and prevent skin irritation by wearing thick, soft, seamless socks. Schedule regular visits with a podiatrist. • Pain relief—To relieve pain, burning, tingling, or numbness, the physician may suggest aspirin, acetaminophen, or nonsteroidal anti-inflammatory drugs (NSAIDs) such as ibuprofen. People with renal disease should use NSAIDs only under a doctor’s supervision. A topical cream called capsaicin is another option. Tricyclic antidepressant medications such as amitriptyline, imipramine, and nortriptyline, or anticonvulsant medications such as carbamazepine or gabapentin may relieve pain in some people. Codeine may be prescribed for a short time to relieve severe pain. Also, mexiletine, used to regulate heartbeat, has been effective in reducing pain in several clinical trials. • Gastrointestinal problems—To relieve mild symptoms of stomach discomfort, doctors suggest eating small, frequent meals, avoiding fats, and eating less fiber. When symptoms are severe, the physician may prescribe erythromycin to speed digestion, metoclopramide for the same reason and to help relieve nausea, or other drugs to help regulate digestion or reduce stomach acid secretion. • Urinary and sexual problems—To treat urinary tract infections, physicians can prescribe antibiotics and suggest drinking plenty of fluids. Several methods are available to treat erectile dysfunction caused by neuropathy, including taking oral drugs, using a mechanical vacuum device, or injecting a vasodilating drug into the penis before intercourse. In women, vaginal lubricants may be useful when neuropathy causes vaginal dryness.

Diadochokinetic rate

U.S. Dept of Health and Human Services. Diabetic Neuropathies: The Nerve Damage of Diabetes. NIDDK, National Diabetes Information Clearinghouse, 2002. PERIODICALS

Podwall D., and C. Gooch. “Diabetic neuropathy: clinical features, etiology, and therapy.” Curr Neurol Neurosci Rep 4. (January 2004): 55–61. Hughes, R. A. C. “Peripheral neuropathy.” BMJ 324 (February 2002): 466–469. Vinik, A. I., R. Maser, B. Mitchell, and R. Freeman. “Diabetic Autonomic Neuropathy.” Diabetes Care 26 (2003): 1553–1579. OTHER

Diabetic Neuropathies: The Nerve Damage of Diabetes. National Institute of Diabetes and Digestive and Kidney Diseases. (January 4, 2004). . ORGANIZATIONS

American Diabetes Association (National Service Center). 1701 North Beauregard Street, Alexandria, VA 22311. (703) 549-6995 or (800) 232-3472 or (800) DIA-BETES. [email protected]. . Centers for Disease Control and Prevention (National Center for Chronic Disease, Prevention and Health Promotion, Division of Diabetes Translation). Mail Stop K-10, 4770 Buford Highway, NE., Atlanta, GA 30341-3717. (301) 562-1050 or (800) CDC-DIAB (800-232-3422). [email protected]. . Juvenile Diabetes Research Foundation International. 120 Wall Street, 19th floor, New York, NY 10005. (212) 785-9500 or (800) 533-2873; Fax: (212) 785-9595. [email protected]. . National Diabetes Education Program. 1 Diabetes Way, Bethesda, MD 20892-3600. (800) 438-5383. . National Institute of Neurological Disorders and Stroke. P.O. Box 5801, Bethesda, MD 20824. (800) 352-9424. .

Greiciane Gaburro Paneto Francisco de Paula Careta Iuri Drumond Louro

❙ Diadochokinetic rate Definition

Diadochokinetic rate (DDK) refers to an assessment tool, used by speech-language pathologists (SLPs), that measures how quickly an individual can accurately produce a series of rapid, alternating sounds. These sounds, also called tokens, may be one syllable such as “puh,” two or three syllables such as “puh-tuh” or “puh-tuh-kuh,” or 278

familiar words such as “pattycake” or “buttercup.” Other names for DDK rate include maximum repetition rate and The Fletcher Time-by-Count Test of Diadochokinetic Syllable Rate, the latter of which is named for the clinician who published DKK rate data in 1972.

Purpose Diadochokinetic rate is one means of assessing oral motor skills. DDK rate provides information about a person’s ability to make rapid speech movements using different parts of his mouth. For example, the sounds “puh,” “tuh,” and “kuh” use the front (the lips), middle (the tip of the tongue), and back of the mouth (the soft palate), respectively. Evaluation of diadochokinetic rate usually occurs as part of an oral motor skills assessment. Other aspects of an oral motor skills assessment include examination of oral facial structures (lips, tongue, jaw, teeth, palate, and pharynx) and evaluation of velopharangeal function and breathing. In general, DDK rates increase as children age and their motor systems mature. Some studies have shown reduced DDK rates in children and adults with speech impairments when compared to rates for individuals with typical speech. Examples of conditions that may be associated with a slower or more variable DDK rate include ataxia, dysarthria, childhood apraxia of speech, and stuttering.

Description The task of measuring DDK rate usually occurs in a single session and takes as little as 15–20 minutes for the SLP to administer and score. Prior to administering the test, the speech-language pathologist will demonstrate the sound(s) to be repeated and allow the patient to complete several practice trials. A trial is defined by a predetermined amount of time or number of repetitions. Generally, the SLP will administer a series of tests, each of which requires the client to produce a different sound or combination of sounds. To measure the DDK rate, a SLP will record how many times the individual repeats the sound or combination of sounds in a given period of time (usually five to 15 seconds). DDK rates are measured in terms of iterations per second (it/s) or in terms of the time required to produce a certain number of iterations of a mono-, bi-, or trisyllabic token. The rate will be calculated and compared to the published norms. The SLP may use specialized recording equipment and a computer software program to record and analyze DDK rate. The DDK rate is calculated by dividing the total number of iterations by the duration of the trial or by determining the time it took the client to make a set number of iterations. The results are scored and compared to the published normative values. For example, in

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Ataxia Childhood apraxia of speech. Dysarthria Stuttering.

the data published by Fletcher (1972), the norm for 20 repetitions of the syllable “puh” for a child at age 10 is 3.7 seconds. Some clients, especially preschool age children, may have difficulty complying with the instructions or completing the DDK tasks. In such cases, real words such as “buttercup,” or “pattycake” may be used to test diadochokinetic rate. Also, preliminary findings from research published by Yaruss and Logan in 2002 indicate that other means of assessing DDK productions in young children, namely, measurement of accuracy and fluency, may be more useful diagnostic tools than standard measures of DDK rate. Resources PERIODICALS

Fletcher, S. G. “Time-by-Count Measurement of Diadochokinetic Syllable Rate.” Journal of Speech and Hearing Research 15 (Dec 1972): 763–70. Yaruss, J. S., and K. Logan. “Evaluating Rate, Accuracy, and Fluency of Young Children’s Diadochokinetic Productions: A Preliminary Investigation.” Journal of Fluency Disorders 27 (2002): 65–86. Williams, P., and J. Stackhouse. “Diadochokinetic Skills: Normal and Atypical Performance in Children Aged 3–5 Years.” International Journal of Language and Communication Disorders 33 (Suppl 1998): 481–6.

Key Terms Benzodiazepines A class of drugs with hypnotic, antianxiety, anticonvulsive, and muscle relaxant properties, used in the treatment of anxiety or sleeping disorders, to relax muscles, or to control seizures.

known as benzodiazepines that depress activity of the central nervous system.

Purpose Diazepam, which is marketed under the brand names of Valium, Diastat, T-Quil, and Valrelease, is taken by millions of people to relieve feelings of anxiety. As well, the drug can lessen muscle spasms and can control some types of seizures. Diazepam is also used to therapeutically lessen the agitation caused during alcohol withdrawal by someone who is physically addicted to alcohol. Additionally, diazepam is used in the treatment of irritable bowel syndrome and to lessen the symptoms of panic attacks.

Description Diazepam is supplied as a tablet, as a capsule that releases the active drug at a slower rate, or as a liquid. All three of these forms of the drug are taken orally. The timerelease capsule should be swallowed whole. Diazepam should be stored at room temperature in a tightly closed container to avoid alteration in the compound due to excessive heat or moisture. Valium is also available in an injectable form.

WEBSITES

Apraxia Kids home page. (May 30, 2004). . ORGANIZATIONS

American Speech Language Hearing Association (ASHA). 10801 Rockville Pike, Rockville, MD 20852-3279. (301) 897-5700 or (800) 638-8255; Fax: (301) 571-0457. [email protected]. .

Dawn J. Cardeiro, MS, CGC

❙ Diazepam Definition

Diazepam is an antianxiety medication that is also useful in the treatment of muscle spasms and some types of seizures. The drug belongs to the class of medications

Recommended dosage Diazepam dosage is determined by a physician taking into account the nature of the problem, severity of the symptoms, and the person’s response to the drug. Typical adult doses range from 2–10 mg taken two to four times a day. Children and elderly adults will typically receive 1–2 mg one to four times daily. The dosage of diazepam typically prescribed by a physician is taken anywhere from one to four times each day, depending on the strength of the individual dose. This maintains the concentration of the drug at a therapeutic level, as diazepam is quickly absorbed from the gastrointestinal tract. Peak levels of the drug are reached within a couple of hours after administration, with levels dropping below therapeutic effectiveness within six to eight hours. Diazepam can be taken with or without food. The liquid form can be mixed with other fluids or select foods such as applesauce.

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Diazepam

Key Terms

Dichloralphenazone, isometheptene, and acetaminophen

Precautions

OTHER

The recommended dosage should not be exceeded, nor should it continue to be taken after the prescribed time. Such abuse can lead to a dependence on the drug, or the establishment of tolerance. As the effectiveness of diazepam is related to its concentration, it is important to take the drug regularly. Doses should not be skipped as this could lead to a worsening of the symptoms.

“Diazepam.” Drugs.com. May 5, 2004 (May 22, 2004.) . “Diazepam.” Medline Plus. National Library of Medicine. May 5, 2004 (May 22, 2004). .

Brian Douglas Hoyle, PhD

Diazepam should not be taken with other central nervous system depressants such as narcotics, sleeping pills, or alcohol. The combinations could lower blood pressure and suppress breathing to the point of unconsciousness and death.

❙ Dichloralphenazone,

Persons taking diazepam should exercise extreme caution when driving or operating machinery. These activities should be avoided during periods of drowsiness associated with diazepam therapy.

Definition

Pregnant and breast-feeding woman should not take diazepam, nor should someone with myasthenia gravis. The drug should be used cautiously in those with epilepsy, as diazepam may trigger an epileptic seizure.

Side effects Some people are allergic to diazepam. In this case, other drugs can be substituted. These include alprazolam (Xanax), chlordiazepoxide (Librium), and triazolam (Halcion). Common side effects from diazepam include drowsiness, dizziness, blurred vision, headache, fatigue, muscle weakness, memory loss, skin rash, diarrhea, dry mouth, stomach upset, decreased sexual drive, and an altered appetite. Less common side effects include jaundice, decreased white blood cell count (leukopenia), insomnia, hallucinations, and irritability.

Interactions Diazepam can interact with other prescription medicines, especially antihistamines, as well as cimetidine (Tagamet), disulfiram (Antabuse), and fluoxetine (Prozac). Additionally, interaction can occur with medications given for the relief of depression, pain, Parkinson’s disease, asthma, and colds, and with muscle relaxants, oral contraceptives, sedatives and sleeping pills, tranquilizers, and even some vitamins. In general, the result of the interaction is to increase the drowsiness caused by diazepam. Resources BOOKS

Diazepam: A Medical Dictionary, Bibliography, and Annotated Research Guide to Internet References. San Diego: Icon Health International, 2004. 280

Isometheptene, and Acetaminophen

Dichloralphenazone, isometheptene, and acetaminophen are a combination medicine indicated for the treatment of symptoms associated with vascular (tension) headaches and migraine. Dichloralphenazone is a general sedative that slows down central nervous system (CNS) function, causing relaxation and minor pain relief. Isometheptene causes narrowing of blood vessels, aiding the specific relief of headache pain. Acetaminophen is a general, mild pain reliever and fever reducer.

Purpose Dichloralphenazone, isometheptene, and acetaminophen do not prevent the occurrence of regular tension headaches or migraines. Rather, they relieve symptoms, including headache, nausea, altered vision, and sensitivity to light and sound at their onset.

Description In the United States, dichloralphenazone, isometheptene, and acetaminophen are sold under the names Amidrine, Duradrin, I.D.A , Iso-Acetazone, Isocom, Midchlor, Midrin, Migrapap, Migquin, Migratine, Migrazone, Migrend, Migrex, Mitride. The medications exert their therapeutic effects individually. Dichloralphenazone aids relaxation, isometheptene relieves the throbbing pain associated with headaches, and acetaminophen acts as a general pain reliever.

Recommended dosage Dichloralphenazone, isometheptene, and acetaminophen are most commonly available together in capsule, tablet, or dissolving tablet form. They are prescribed by physicians in varying dosages. Dichloralphenazone, isometheptene, and acetaminophen are not indicated for routine use or headache prevention. For the treatment of tension headaches and

GALE ENCYCLOPEDIA OF NEUROLOGICAL DISORDERS

Migraine Recurrent severe headaches generally accompanied by an aura (classic migraine), nausea, vomiting, and dizziness.

migraines, they should be taken at the onset of headache symptoms or at the first warning signs of migraine. The usual initial dose for adults is one to two capsules. Treatment including dichloralphenazone, isometheptene, and acetaminophen may be appropriate for some children, but only when advised by a physician. The maximum daily dose for anyone taking dichloralphenazone, isometheptene, and acetaminophen usually is not greater than six to eight capsules. A double dose of dichloralphenazone, isometheptene, and acetaminophen should not be taken at one time. If one dose fails to relieve symptoms associated with tension headache or migraine, follow instructions provided by the prescribing physician for taking supplemental doses every few hours. Do not take dichloralphenazone, isometheptene, and acetaminophen for several days in a row, even if symptoms persist, unless instructed by a physician. Any persistent, severe headache should be evaluated by a physician, especially if accompanied by fever, visual disturbances, confusion, stiff neck, or numbness and weakness on one side of the body.

The effect of dichloralphenazone, isometheptene, and acetaminophen during pregnancy has not been fully established, but research demonstrates that the medications are passed into breast milk. Patients who become pregnant while taking dichloralphenazone, isometheptene, and acetaminophen should contact their physician.

Side effects Patients and their physicians should weigh the risks and benefits of dichloralphenazone, isometheptene, and acetaminophen before beginning treatment. Most patients tolerate combination medications with dichloralphenazone, isometheptene, and acetaminophen well, but may experience a variety of mild to moderate side effects. Some possible side effects, such as upset stomach and nausea mirror the symptoms associated with migraine. Common side effects that do not usually require medical attention include: • diziness or unsteadiness • sleepiness or drowsiness • feeling of warmth or heaviness • flushing

Precautions Dichloralphenazone, isometheptene, and acetaminophen may cause drowsiness and sleepiness for several hours. Caution is necessary to determine if it is safe to drive a car or operate machinery. It is necessary to consult a physician before taking dichloralphenazone, isometheptene, and acetaminophen with certain non-perscription medications. While taking dichloralphenazone, isometheptene, and acetaminophen, patients should avoid alcohol and CNS depressants (medicines that can make one drowsy or less alert, such as antihistimines, sleep medications, and some pain medications). They can exacerbate side effects such as drowsiness, nausea, and loss of coordination. Avoid additional general pain relievers containing acetaminophen (such as Tylenol) while using a dichloralphenazone, isometheptene, and acetaminophen combination medicine. Dichloralphenazone, isometheptene, and acetaminophen may not be suitable for persons with a history of asthma or other chronic lung diseases, liver disease, kidney disease, mental illness, high blood presure, seizures,

• tingling feeling • excessive sweating • diarrhea Other, less common side effects of dichloralphenazone, isometheptene, and acetaminophen may be serious. The sudden onset of some severe side efects may indicate an allergic reaction. Contact the prescribing physician immediately if any of the following symptoms occur: • pinpoint red spots on skin • dark stools • rash, lumps, or hives • redness or swelling of the face, lips, or eyelids • change in vision • wheezing and difficulty breathing • chest pain or tightness in the chest • irregular heartbeat • faintness or loss of consciousness • sudden or severe stomach pain • fever

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Dichloralphenazone, isometheptene, and acetaminophen

Key Terms

angina (chest pain), irregular heartbeats, or other heart problems. Persons who have had a stroke or are obese should avoid taking dichloralphenazone, isometheptene, and acetaminophen. Patients should notify their physician if they consume a large amount of alcohol, have a history of drug use, are nursing, pregnant, or plan to become pregnant.

Dichloralphenazone

Interactions

Purpose

Dichloralphenazone, isometheptene, and acetaminophen receptor agonists may have negative interactions with antibiotics, antidepressants, anticoagulants, antihistimines, asthma medications, and monoamine oxidase inhibitors (MAOIs). Patients should not take dichloralphenazone, isometheptene, and acetaminophen for several weeks after stopping treatment with MAOIs. Dichloralphenazone, isometheptene, and acetaminophen combination medications should not be used in conjunction with other migraine treatment medications unless otherwise directed by a physician.

Description Dichloralphenazone is not indicated for routine use. The medication should be taken only at the onset of pain, tension headache symptoms, or at the first warning signs of migraine.

Resources BOOKS

Lang, Susan, and Lawrence Robbins. Headache Help: A Complete Guide to Understanding Headaches and the Medications That Relieve Them. Boston: Houghton Mifflin, 2000.

Recommended dosage

OTHER

“Isometheptene, Dichloralphenazone, and Acetaminophen.” Web MD. (April 23, 2004). . “Isometheptene, Dichloralphenazone, and Acetaminophen (Systemic).” Yahoo Drug Index. (April 12, 2004). . ORGANIZATIONS

ACHE (American Council for Headache Education). 19 Mantua Road, Mt. Royal, NJ 08601. (856) 423-0258. . National Headache Foundation. 428 W. St. James Place, 2nd Floor, Chicago, IL 60614. (703) 739-9384 or (888) NHF5552. . Migraine Awareness Group. 113 South Saint Asaph Street, Suite 300, Alexandria, VA 22314. (703) 739-9384. .

Adrienne Wilmoth Lerner

❙ Dichloralphenazone Definition

Dichloralphenazone is a general sedative-hypnotic that slows central nervous system (CNS) function, causing relaxation and pain relief. It is primarily indicated as a component of a drug that is used in the treatment of tension (muscle contraction) and vascular (migraine) headaches. Additional uses for dichloralphenazone include sedation and pain relief, and treatment for symptoms associated with insomnia. 282

The combination medication, including isometheptene, dichloralphenazone, and acetaminophen, is used to treat tension and vascular headaches. Although the combination does not prevent the occurrence of tension headaches or migraines, isometheptene, dichloralphenazone, and acetaminophen act to relieve pain at its onset. The combination also relieves some symptoms associated with migraine such as altered vision and sensitivity to light and sound.

Dichloralphenazone is most commonly available in capsule form, and is prescribed by physicians in varying dosages. The usual dose for adults is one to two capsules. Under the supervision of a physician, treatment that includes dichloralphenazone may be appropriate for some children. A double dose of dichloralphenazone should not be taken. If the first dose fails to relieve pain or symptoms associated with tension headache or migraine, the patient should follow instructions provided by the prescribing physician for taking supplemental doses every few hours. If pain persists for several days, this medication should not be taken without consulting the prescribing physician.

Precautions Dichaloralphenazone may cause drowsiness and sleepiness for several hours. Extreme caution should be used when driving or operating machinery. A physician should be consulted before taking any form of dichloralphenazone with certain non-prescription medications. Patients taking dichloralphenazone should avoid alcohol and CNS depressants, including medicines that can make one drowsy or less alert such as antihistimines, sleep medications, and some pain medications. These medicines can exacerbate the side effects of dichloraphenazone. Dichloralphenazone may not be suitable for persons with a history of seizures, stroke, asthma or other chronic lung diseases, liver disease, kidney disease, mental illness, high blood pressure, angina (chest pain), irregular heartbeats, or other heart problems. Patients should notify their physician if they smoke, consume a large amount of alcohol, have a history of drug use, are nursing, pregnant, or

GALE ENCYCLOPEDIA OF NEUROLOGICAL DISORDERS

Key Terms Migraine A recurring, severe vascular headache, often accompanied by stomach upset and visual sensitivity to light, thought to be caused by changes in blood flow and certain chemical changes in the brain. Sedative Medications that quiet nervous system excitement, producing a relaxed state.

plan to become pregnant. The effect of dichloralphenazone during pregnancy has not been fully established. Patients who become pregnant while taking dichloralphenazone should contact their physician.

Side effects Patients and their physicians should weigh the risks and benefits of dichloralphenazone before beginning treatment, as some forms of dichloralphenazone may be habit forming. Most patients tolerate combination medications with dichloralphenazone well. However, some people may experience a variety of mild to moderate side effects. A few possible side effects such as headache, upset stomach, and nausea mirror symptoms associated with tension headaches and migraine. Common side effects that do not usually require medical attention include: • dizziness or unsteadiness • sleepiness or drowsiness • feeling of warmth or heaviness • increased sweating • flushing • tingling feeling • diarrhea

• persistent fever

Interactions Dichloralphenazone may have negative interactions with antibiotics, antidepressants, anticoagulants, antiepileptic drugs (AEDs), anticonvulsants, antihistimines, asthma medications, and monoamine oxidase inhibitors (MAOIs). Patients should not take dichloralphenazone for several weeks after stopping treatment with MAOIs. Dichloralphenazone should not be used in conjunction with other migraine treatment medications unless otherwise directed by a physician. Resources BOOKS

Lang, Susan. Headache Help: A Complete Guide to Understanding Headaches and the Medications That Relieve Them—Fully Revised and Updated. New York: Houghton Mifflin, 2000. Robbins, Lawrence. Management of Headache and Headache Medications. New York: Springer Verlag, 2000. OTHER

“Isometheptene, Dichloralphenazone, and Acetaminophen (Systemic).” Medline Plus Drug Information. National Library of Medicine. May 6, 2004 (May 22, 2004). . ORGANIZATIONS

ACHE (American Council for Headache Education). 19 Mantua Road, Mt. Royal, NJ 08601. (856) 423-0258. . National Headache Foundation. 428 W. St. James Place, 2nd Floor, Chicago, IL 60614. (703) 739-9384 or (888) NHF5552. . Migraine Awareness Group. 113 South Saint Asaph Street, Suite 300, Alexandria, VA 22314. (703) 739-9384. .

Other, less common side effects of dichloralphenazone could indicate a potentially serious condition. The sudden onset of some severe side effects may indicate an allergic reaction. If any of the following serious side effects occur, the prescribing physician should be contacted immediately:

Adrienne Wilmoth Lerner

❙ Diencephalon

• rash, lumps, or hives • redness or swelling of the face, lips, or eyelids • change in vision • wheezing and difficulty breathing • chest pain or tightness in the chest • irregular heartbeat • faintness or loss of consciousness

Definition

The diencephalon is a complex of structures within the brain, whose major divisions are the thalamus and hypothalamus. It functions as a relay system between sensory input neurons and other parts of the brain, as an interactive site for the central nervous and endocrine systems, and works in tandem with the limbic system.

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Diencephalon

• sudden or severe stomach pain

Diencephalon

Description The diencephalon is composed of several structures, the whole about the size of an apricot, situated near the core center of the brain, just above the brainstem. It is made up of the medulla oblongata, pons, and midbrain, below the telencephalon, the most basal part of the cerebrum. The two major components of the diencephalon are the thalamus and the hypothalamus. Other important structures within the diencephalon complex are the epithalamus, subthalamus, third ventricle, mammillary bodies, posterior pituitary gland, and the pineal body. The diencephalon interconnects with a larger, surrounding array of structures called the limbic system, which is the seat of emotions and memory. The diencephalon functions in the following ways: • As a junction and relay system that receives and filters afferent (incoming) sensory information, then relays it on to other parts of the brain, mainly the cerebral cortex, but also to the cerebellum and brainstem. • As an interactive site between the central nervous system and the endocrine system. • As an interactive complementary to the limbic system. The upper part of the diencephalon, making up about 80% of its mass, is the thalamus, a small pillow of neural gray matter divided into two egg-shaped lobes. The lobes’ long axes run toward the front and back of the head, and are connected to each other by a small stalk, the intermediate mass. The two thalamic lobes are filled with numerous pairs of nuclei, which are concentrations of synapsing afferent, or incoming, and efferent, or outgoing, neurons. Numerous such nuclei are situated throughout the brain. The thalamic nuclei are named and classified according to their positions within the thalamus (medial, lateral, central, etc.), by their neural connections, and by their functions. In terms of function, there are three types of thalamic nuclei: sensory, motor, and arousal. Layered sheets of myelinated axons, the internal thalamic medullary laminae, run vertically through the lobes of the thalamus. These laminae are full of neurons that interconnect various thalamic nuclei. The edges of the internal lamina reach the surfaces of the lobes. They show as narrow, whitish, cable-like bands, running across either lobe from its posterior underside, across the top, and forward, bifurcating into two bands (two vertical layers) toward the front. The main lamina divide the lobes of the thalamus into portions containing the medial and lateral geniculate nuclei, while the anterior bifurcations enclose the anterior nuclei. The thalamus, the basal ganglia, and the cerebellum, which is the main movement coordination center of the brain, are neurally linked to the cerebral motor cortex in 284

reciprocal, or feedback, fashion. Together, they regulate and fine-tune motor functions. The basal ganglia, which are part of the telencephalon, are groupings of gray matter within the white matter of the cerebral hemispheres. The basal ganglia function directly with the cerebellum to modify and fine-tune body movements. A small part of the diencephalon, the epithalamus, extends rearward from, and slightly higher than, the thalamus. It holds the habenular nuclei, the stria medullaris thalami nerve tracts, and the pineal body, or epiphysis. The habenular nuclei play a role in emotional responses to odors. They receive afferent nerves from the septum, a complex of structures within the telencephalon and limbic system, and from the lateral preoptic nuclei of the basal forebrain, which is the lowermost region of the cerebrum; the stria medullaris tracts and the basal ganglia are the conduits. The habenular nuclei send efferents to the interpeduncular nucleus of the midbrain via the habenulo-interpeduncular nerve tract. The pea-sized, conically shaped pineal body, on a short stalk, projects rearward and downward from the epithalamus. The pineal is a gland-like organ whose functions are still only poorly understood. It is a functional, light-sensitive remnant of an ancient and much more complex system of visually oriented organs, the pineal complex. The pineal is neurally connected with the suprachiasmatic nuclei of the hypothalamus, which hold the circadian internal clock. This is located just above the optic chiasma, the point at which the optic nerves from both eyes cross. The human pineal secretes melatonin, a hormone that seems to have a calming effect on the nervous system. The pineal, in response to the level of daylight, may induce sleepiness by increasing the output of melatonin. All sensory input, except the olfactory (smell), passes through the thalamus, where it is filtered, integrated, and passed on to proper sites in the brain, most of them within the cerebral cortex. The route is as follows: • Impulses from the auditory organs synapse in the medial geniculate thalamic nuclei, where they are sent to the auditory centers of the cerebral cortex. • Impulses from the eyes, via the optic nerves, synapse in the lateral geniculate thalamic nuclei, and are sent on to the calcarine cerebral cortex. • Other sensory input synapses in the ventral posteromedial thalamic nuclei, which receive, process, and pass on somatosensory input from the head, while the ventral posterolateral thalamic nuclei do likewise with input from the rest of the body. • The thalamic nuclei also receive input from subcortical sources and feedback from the cortical areas. These operate in tandem to filter and control input to the cortex.

GALE ENCYCLOPEDIA OF NEUROLOGICAL DISORDERS

Autonomic nervous system A complex of nerve tracts, nuclei and organs within the brain that maintain homeostasis, or the functioning of body systems at proper levels. Hypothalamus The lowermost part of the diencephalon, containing several nuclei, nerve tracts, and the pituitary gland; it is the regulatory seat of the autonomic nervous system. Limbic system A complex of nerve tracts and nuclei that function as the seat of memory and emotions, containing the fornix, hippocampus, amygdala, and the cingulate gyrus. Thalamus A small mass of gray matter composing the upper structure of the diencephalon, divided into two lobes and filled with numerous thalamic.

The ventral anterior and ventral lateral thalamic nuclei, involved with motor function, receive sensory input relayed through the basal ganglia and through the superior cerebellar peduncle, the main neural tract connecting the cerebellum and the red nuclei. The ventral anterior and ventral lateral thalamic nuclei project to the premotor and motor cerebral cortex. In addition, the ventral anterior thalamic nuclei are the main relay nuclei between the thalamus and the limbic system, receiving the mammillothalamic nerve tract from the mammillary bodies in the hypothalamus and projecting to the cingulate gyrus. The cingulate gyrus, which is not a part of the diencephalon, is the part of the cerebrum closest to the limbic system, and serves to neurally connect the thalamus and hippocampus. The cingulate gyrus associates memories and emotional responses with smells, sights, and pain, and allows movement of attention among objects or ideas. The medial dorsal thalamic nuclei receive nerve tracts from the amygdala of the limbic system and send efferents to the prefrontal cerebral cortex (not part of the diencephalon), which has numerous feedback connections with the thalamus, amygdala, and other subcortical structures. The anterior thalamic nuclei connect with the mammillary bodies of the hypothalamus, and through them, via a nerve tract, the fornix, with the hippocampus and the cingulate gyrus. The centromedian thalamic nuclei regulate excitability levels within the cerebral cortex and thus play a major role in arousal and alertness. The centromedian thalamic nuclei receive motor-related input from the basal ganglia, cerebellum, and the reticular formation of the brainstem

The dorsomedial thalamic nuclei are involved with emotional arousal and the expression of emotionally based behavior, as well as memory, foresight, and feelings of pleasure. These nuclei receive input from many sites and interconnect with the prefrontal cerebral cortex. That part of the diencephalon immediately below the two lobes of the thalamus is the subthalamus. It contains several nerve tracts and the subthalamic nuclei. Small portions of the red nuclei and the substantia nigra of the midbrain reach into the subthalamus. The subthalamic nuclei are interconnected with the basal ganglia and are involved in controlling motor functions. The hypothalamus is the lowermost structure of the diencephalon. The thalamus, epithalamus, and hypothalamus surround and define most of the third ventricle of the brain, which, like all the ventricles, is filled with cerebrospinal fluid. The third ventricle communicates with the lateral ventricles and, via the cerebral aqueduct, with the fourth ventricle. The hypothalamus contains several nuclei, nerve tracts, and the pituitary gland. It is the regulatory seat of the autonomic nervous system, while the hypothalamus and the pituitary are the major sites in which the two regulatory systems of the body, the central nervous system and the endocrine system, interact. The hypothalamus regulates the production of pituitary hormones, influencing and being influenced by emotional states, physical appetites, autonomic functions, temperature control, and diurnal rhythms. It is thus the main control center for homeostasis, or keeping physiological maintenance systems functioning at optimal states. Efferent nerves from the hypothalamus extend into the brainstem and the spinal cord, where they synapse with neurons of the autonomic nervous system, which regulates a number of involuntary functions, among them the rate of heartbeat, urine release, and peristalsis. The hypothalamus responds to sensations of temperature extremes, the posterior hypothalamus stimulating muscle shivering to deal with cold, via efferent neurons to motor neurons within the spinal cord, and the anterior hypothalamus producing sweating as a reaction to overheating. The pair of globular mammillary bodies are partially embedded in the underside of the hypothalamus. They are

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Diencephalon

Key Terms

and midbrain, and send efferent nerves to the cerebral cortex. The reticular formation is a network of nerves running through the brainstem and hindbrain, and containing the reticular activating system, which plays a key role in inducing arousal and alertness in tune with the circadian rhythm (sleeping and waking cycles). The reticular thalamic nuclei, which receive neural input from the reticular formation, regulate general thalamic output in accordance with the circadian rhythm.

Diencephalon

involved in olfactory reflexes and emotional responses to odors. Also on the underside of the hypothalamus, and toward the front, is the optic chiasma, where the two optic nerve cables of the eyes cross. From the floor of the hypothalamus, the posterior pituitary gland, or neurohypophysis, extends forward and downward at the end of a long peduncle or stalk, the infundibulum. Efferent hypothalamic nerves extend through the infundibulum to the posterior portion of the pituitary gland, others extend to the trigeminal and facial nerve nuclei, to help control the head muscles involved in swallowing. The posterior pituitary is an extension of the hypothalamus, but the anterior part of the pituitary is glandular tissue with an embryonic origin separate from that of the posterior pituitary. During embryonic development, the anterior and posterior lobes of the pituitary eventually meet and fuse. The hypothalamus plays a pivotal role in regulating the endocrine system via its control of the pituitary gland’s production of several hormones, while the hypothalamus is influenced in turn by hormones in the bloodstream and by nerve input. A partial list of hormones secreted by the pituitary includes cortisol, prolactin, antidiuretic hormone (ADH), oxytocin, growth hormone (GH), thyroid stimulating hormone (TSH), adrenocorticotropic hormone (ACTH), lipotropins, beta-endorphins, melanocyte stimulating hormone, luteinizing hormone, and follicle stimulating hormone. Hormones influence functions as diverse as metabolism, growth and maturation, reproduction, dealing with stress, urine production, ion balance, sexual development, and sexual function. The hypothalamus regulates physical appetites for food, water, and sex. Afferent fibers synapsing in the hypothalamus carry input from the internal organs, the taste receptors of the tongue, the limbic system, the nipples, and the external genitalia. The hypothalamus responds to and accords with emotional states, and thus plays a major role in affecting emotions and moods, among them sexual pleasure, tranquility, rage, and fear. The hypothalamus contributes to the regulation of the circadian rhythm via an internal clock within the suprachiasmatic nuclei. This internal clock communicates with the reticular formation of the midbrain. The reticular formation contains the reticular activating system, which plays a key role in inducing arousal and alertness, in tandem with the circadian rhythm. The diencephalon is interconnected with a surrounding complex of brain structures, the limbic system, which functions as the center of emotional states and responses, and of memory. Besides the various structures within the diencephalon, the limbic system includes the olfactory 286

cortex, hippocampus, amygdala, cingulate gyrus, septal nuclei, the dorsomedial nuclei of the thalamus, and the anterior nuclear complex of the thalamus. Memories of vividly emotional experiences are recorded and kept within easy reach of consciousness within the limbic system. Connections between, and functions of, the hypothalamus and limbic system are intimately intertwined. The ventral anterior thalamic nuclei are the main relay nuclei connecting the thalamus and the limbic system, receiving the mammillothalamic tract and projecting to the cingulate gyrus. The olfactory sense is the only one whose neurons directly connect with a processing center within the limbic system and outside the thalamus. Within the hypothalamus, relayed olfactory impulses are used to regulate appetite and sexual behavior, and to regulate autonomic reactions initiated by odors. Since the limbic system processes memory and stores important memories, the direct connection of the olfactory neurons to the limbic system helps explain why odors serve as alarms (e.g., the odor of smoke) and can trigger strong emotional responses and vivid, detailed memories of events and emotional states. The hippocampus, the main processor of memory, is a paired structure looping over the tops of the thalamic lobes and rearwards, curving downward and forward and ending at the paired, globular, cherry-sized amygdala, below and in front of the hypothalamus. The amygdala connect with the hippocampus, the septal nuclei, the prefrontal area of the cerebrum, and the medial dorsal nucleus of the thalamus. The amygdala also send nerves to the hypothalamus via the ventral amygdalofugal pathway. The amygdala are centers for associating strong emotions, good or bad, with memories of the experiences that triggered those emotions. Fear responses and fear-charged memories are centered in the amygdala, which can retain vivid memories of traumatic experiences, and initiate the survival fight-or-flight response. The hippocampus sends efferents, via a cable of nerves, the fornix, to the mammillary bodies within the hypothalamus. The mammillary bodies send efferents to the anterior nuclei of the thalamus via the mammillothalamic tract. Resources BOOKS

Ackerman, Diane. An Alchemy of Mind: The Marvel and Mystery of the Brain. New York: Scribner, 2004. Mai, Juergen, Joseph Assheuer, and George Paxinos. Atlas of the Human Brain. Philadelphia: Academic Press, 1997; Deluxe Edition, 1998. PERIODICALS

Scientific American Mind: The Brain, A Look Inside, special edition, vol. 14, no 1, 2004.

GALE ENCYCLOPEDIA OF NEUROLOGICAL DISORDERS

Brain Structure and Function. University of Idaho. (May 20, 2004). . DienCephalon. Geocities. (May 20, 2004.) . The Human Brain: Chapter 5: The Cerebral Hemispheres. Virtual Hospital. (May 20, 2004). . The Hypothalamus and Pituitary Gland: Introduction and Index. Colorado State University. (May 20, 2004). . The MIND Institute Mental Illness and Neuroscience Discovery. (May 20, 2004). . Neuroanatomy and Neuropathology on the Internet. (May 20, 2004). . Penn State Hershey Medical Center: FRED (Faculty Research Expertise Database). (May 20, 2004). . “A Primate Brain Information System.” Braininfo. (May 20, 2004). . The Washington University School of Medicine Neuroscience Tutorial. (May 20, 2004). . ORGANIZATIONS

The MIND Institute: Mental Illness and Neuroscience Discovery. 801 University Boulevard SE Suite 200, Albuquerque, NM 87106. (505) 272-7578; Fax: (505) 272-7574. [email protected]. . Society for Behavioral Neuroendocrinology. 4327 Ridge Road, Palmyra, VA 22963. [email protected]. .

Kevin Fitzgerald

❙ Diet and nutrition Definition

Adequate nutrition and a well-balanced diet in every phase of life are essential requirements for normal development and growth, health maintenance, and disease prevention, as well as for the recovery from illness or injury. The human organism is a dynamic system, constantly using stored energy to perform physiologic functions such as blood circulation, respiration, immune surveillance and defense against infections, synthesis of proteins, hormones, and neurotransmitters necessary for muscle activity, sensory perception, thought processing, digestion of

food and elimination of body wastes, cell and tissue detoxification, and DNA repair. Food is the main source of the micronutrients the organism utilizes to perform these vital functions, thus keeping the many physiologic systems in a state of homeostasis, or dynamic functional balance.

Description Micronutrients are substances the body extracts from food through digestion, the process of breaking down large and complex molecules of food into more simple and smaller ones. Micronutrients are then absorbed through the walls of the small intestine into the blood vessels to be distributed to and processed by different organs and tissues. Different classes of micronutrients are used for several different purposes. For instance, some micronutrients such as vitamins are essential for cellular protection against naturally occurring metabolic toxins formed as a byproduct of cellular activity, or against toxins derived from the environment, such as pollution, chemicals, solar radiation, or drugs. Micronutrients are divided in the following categories: amino acids, fatty acids, sugars or carbohydrates, vitamins, and minerals. Amino acids are the building blocks of all types of proteins that constitute cells, organs, tissues, and muscles. Some proteins are mediators of signals between cells of different organs, regulating intracellular physiology and growth. Although approximately 300 amino acids are known in nature, the human body only utilizes about 20 of them. The body itself manufactures half of the amino acids required by humans to make proteins. However, 10 of these are called essential amino acids because humans depend on their presence in food, since the body cannot adequately manufacture them. Eight of the 10 essential amino acids must be present in the diet throughout life, whereas two are necessary during development and growth, or when tissue repair is needed. Some amino acids are created in the brain and play an important role in the regulation of mood, cognitive function, attention, and sleep pattern. The synthesis of neurotransmitters, chemical messengers in the brain that regulate neural activity, is also dependent on adequate dietary intake of essential amino acids. Examples of neurotransmitters are acetylcholine, gamma-aminobutyric acid (GABA), dopamine, and serotonin. The main source of essential amino acids is animal protein such as fish, meat, milk, and eggs. Plants are also a source of amino acids, although none contain all of the essential amino acids. It is important, therefore, to combine different types of plants within the same meal, such as nuts, beans, grains, fruits, especially in vegetarian diets. Enzymes are another important type of protein that regulates all metabolic events. Some enzymes are responsible for the detoxification of cells and tissues, and

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WEBSITES

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Key Terms Amino acid An organic compound composed of both an amino group and an acidic carboxyl group. Amino acids are the basic building blocks of proteins. There are 20 types of amino acids (eight are “essential amino acids” that the body cannot make and must therefore be obtained from food). Antioxidant Any substance that reduces the damage caused by oxidation, such as the harm caused by free radicals. Free radical An unstable molecule that causes oxidative damage by stealing electrons from surrounding molecules, thereby disrupting activity in the body’s cells. Homeostasis The balanced internal environment of the body and the automatic tendency of the body to maintain this internal “steady state.” Also refers to the tendency of a family system to maintain internal stability and to resist change. Neurotransmitter A chemical messenger that transmits an impulse from one nerve cell to the next.

the activation of medications, while others are involved in the regulation of the cellular cycle during cell proliferation. Some enzymes are essential for the digestion of larger nutrients such as dietary proteins, carbohydrates, and fatty acids, and are known as digestive enzymes. Other groups of enzymes regulate the synthesis and degradation of other enzymes involved in the processing and transport of micronutrients. Deficiency in digestive enzymes causes slow and incomplete digestion of larger nutrients, thus reducing the availability of micronutrients to the body and resulting in a nutritional deficit. Although the body manufactures some digestive enzymes, a diet rich in fruits and vegetables provides a reliable source for digestive enzymes. Papaya, pineapple, cucumber (eaten with the skin), tomatoes, and green leafy vegetables are especially good sources for digestive enzymes. Another frequent cause of nutritional deficiency is malabsorption of nutrients in the intestinal tract due to parasite infestation, infections, or disruption of the normal intestinal microorganism balance by some medications. Normally, a mixed population of bacteria permanently lives in the intestinal mucosa, helping to break down some larger molecules such as complex carbohydrates. When 288

this balance is disrupted, even though the daily diet contains the correct amounts of all necessary nutrients, nutritional deficiencies may occur due to the inability of the intestinal tract to absorb molecules that are not broken down by the beneficial bacteria. Fatty acids are the components of lipids or fats that may be combined with proteins and/or sugars to form a variety of functional and structural molecules such as cholesterol, hormones, and enzymes. Fatty acids are also an important source of body energy and are stored in the adipose tissue (i.e., fat cells). Lipoproteins (such as cholesterol) are present in the structure of cell membranes and in blood plasma, and have a variety of other functions. For example, cholesterol is a precursor of bile acid and of steroid hormones such as testosterone, progesterone, and estrogen. Myelin, the white substance that involves nerve fibers as a multi-layered sheath, is constituted of lipids and proteins, and is essential for normal neural signal transmission, and muscle control and coordination. Fatty acids are present in whole milk, butter, fish, seafood, lard, meat, vegetable oils, margarine, nuts, olives, corn, soybean, and grains. Carbohydrates encompass a variety of sugar molecules that play a multitude of roles in body physiology and are also a structural component of the cell membrane. Carbohydrates supply and store energy, aid in intercellular communication, and regulate many metabolic events in the body. The digestive process transforms carbohydrates into glucose, the main source of energy used by cells. Glucose, a simple sugar, is a component of many proteins known as glycoproteins, and is also present in the molecular structure of DNA as pentose. The central and peripheral nervous systems demand a constant supply of glucose in the blood, as does the muscular system. The body stores glucose in the form of glycogen that can be promptly mobilized when the level of glucose in the blood falls. Glycogen is mainly stored in skeletal muscles and in the liver, but it is also present in small amounts in virtually every cell of the body. Carbohydrates are present in milk, fruits, potatoes, cereals, sugar, and honey. Whole grains, lettuce, and fruits also contain a type of fibrous carbohydrate humans cannot digest, known as cellulose. Nevertheless, cellulose helps digestion because these fibers stimulate movement of the intestinal tract, preventing constipation and removing pathogenic germs. The body needs to protect its cells and DNA from the damage oxygen and free radicals can do. Free radicals are highly reactive substances that form when oxygen interacts with other molecules during digestion or other cellular processes. To combat this damage, the body uses a defense system of antioxidant molecules that react safely with the free radicals. Some antioxidant molecules are naturally occurring enzymes. Vitamins are another important source of antioxidants.

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Vitamin C (ascorbic acid) and B-complex vitamins (thiamine, niacin, riboflavin, biotin, folic acid, cobalamin, pyridoxine, and pantothenic acid) are water-soluble vitamins. Since kidneys easily eliminate water-soluble vitamins through the urine, they must be present in the daily diet because only trace amounts are stored in the organism. The main dietary sources of vitamin C are tomatoes, green leafy vegetables, and citrus fruits such as oranges, although other fruits and vegetables do contain smaller amounts of vitamin C. Raw meat and fish also contain vitamin C that is lost in the cooking process. Vitamin C protects cells against oxidation, helps collagen formation, and the transformation of cholesterol into bile acids. The detoxification properties of vitamin C help in the elimination of the toxins and free radicals that build up in the extracellular fluids and in cells during infections. B-complex vitamins participate as co-factors in a vast number of enzyme activities and act as co-antioxidants as well. Some B vitamins are required for red blood cell formation, while others are required for regulation of plasma cholesterol levels, energy release in tissues, amino acid synthesis, embryo development, brain development and neuronal activity, bone marrow formation, and infection resistance. Additionally, some B vitamins promote myelin sheath formation around nerve fibers and neurons during brain development in the fetus and during child growth as well. The main dietary sources of B-complex vitamins are whole milk, chicken, pork, egg, seafood, meat, liver, corn, wheat and whole grains, green leaves, and legumes. As not all B vitamins are present in each of these foods, it is important to keep a well-balanced and varied diet. Strict vegetarians, especially vegans, need supplementation of some B vitamins such as biotin and cobalamin as animal products are eliminated as a dietary source. The fat-soluble vitamins are vitamins A, D, E, and K. The precursors of these vitamins are present in food, and are transformed by the body into the active vitamin form. Dietary precursors of vitamin A are beta-carotene and other carotenes found in carrots, yellow fruits and seeds, as well as in dark green vegetables. Retinol, found in animal products such as meat, fish, egg yolk, whole milk, and butter, is vitamin A itself. Vitamin A is essential for normal fetal development, child growth, tissue repair,

healing, and renewal, vision, cell protection against free radicals, and reproduction. Beta-carotene shows several benefits of its own, independently of being converted into vitamin A by the body. Some scientific evidence shows that adequate levels of beta-carotene in the diet help to prevent chronic and degenerative diseases such as skin cancer, cardiac diseases, and cataracts. This vegetable precursor of vitamin A also has its own antioxidant activity, and enhances immune system function. Whereas excessive intake of retinol may cause liver and nerve cell toxicity, beta-carotene does not offer such a risk. Vitamin D is, in fact, a group of molecules that function as hormones. The dietary precursor of vitamin D in plants is known as ergocalciferol. Animal products contain some preformed active molecules of vitamin D. However, the main source of vitamin D in the organism is in the form of an intermediate molecule of cholesterol that is converted into calcitriol in the skin through the action of solar radiation. Long winter months in the northern hemisphere or little exposure to sunlight sometimes lead to deficiency of vitamin D, thus requiring greater dietary intakes of animal products such as fatty fish and egg yolk. Calcitriol, one active form of vitamin D, regulates the synthesis of proteins responsible for calcium and phosphate absorption in the intestinal tract. Vitamin D also regulates the levels of calcium in blood plasma, and helps the mineralization of bones. This micronutrient is essential for normal skeletal development of infants and children, and to prevent osteoporosis in adults, especially women and elderly men. Tocopherols are different forms of vitamin E, such as alpha and beta tocopherols, and are important antioxidants that protect cholesterol and fatty acids against peroxidation, the chemical process that transforms lipids into rancid fat. Peroxidation of circulating cholesterol causes progressive vascular obstruction, which may lead to heart attack or stroke. Vitamin E also protects fatty acids and lipids that are components of cell membrane structure, thus maintaining the cell’s normal functionality. The best dietary sources of vitamin E are vegetable oils. Vitamin K occurs as phylloquinone in plants, and as menaquinone in bacteria of the intestinal flora. It is essential for the right formation of clotting factors, the proteins responsible for normal blood coagulation. Dietary sources are spinach, cabbage, egg yolk, and liver, although the normal intestinal bacterial flora constitutes a regular source of the vitamin as well. Discrete (trace) amounts of some minerals are also vital for cell metabolism, neural and muscle activity, bone development and maintenance, electro-chemical reactions, and transport of nutrients and metabolic waste through the cell membrane. The most important minerals are calcium, phosphorus, potassium, magnesium, sodium, and iron.

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Vitamins neutralize free radicals and protect tissue integrity and function. They are also essential for a number of other cellular functions such as tissue renewal and healing, red blood cell production, body resistance to infections, brain and muscle activity, DNA replication during cell cycle, adequate regulation of several metabolic events, recovery from disease, and prevention of chronic disease. Vitamins are divided in two categories according to their solubility: water-soluble vitamins and fat-soluble vitamins.

Disc herniation

Calcium and phosphorus are required by a variety of body functions such as bone formation and maintenance, neural signal transmission or synapses, smooth muscle contraction, and skeletal muscle activity. They also regulate glandular and enzymatic activity. Major sources of these nutrients are milk and dairy products. Magnesium works together with calcium, regulating calcium transport into cells and to and from bones. Magnesium controls the levels of calcium transported to heart tissue, maintaining the heartbeat in a steady pace. Magnesium is also important in cells of the immune system such as lymphocytes, in skeletal muscles, and as a facilitator of oxygen delivery. Magnesium participates in the production of ATP (adenosine triphosphate), the source of energy utilized by cells. Sodium and potassium regulate levels of fluids entering and leaving the cells, and moving between blood vessels and the lymphatic system, and are, therefore, important agents in the regulation of blood pressure. Iron is an essential component of red blood cells (hemoglobin), which transport oxygen to all tissues. Iron is stored in the plasma in proteins known as ferritin. Adequate plasma levels of ferritin are required for hematopoiesis, or blood formation. However, excess ferritin in plasma increases cholesterol peroxidation, leading to cardiovascular disease. Trace amounts of minerals are present in fruits and other vegetables, as well as in animal products such as seafood, fish, liver, milk, meat, eggs, and poultry. Dieticians are the best advisors when a specific diet is important, such as during pregnancy, or in infancy and early childhood development, in order to prevent nutritional deficits. Physicians can refer patients to trusted dieticians. Elderly citizens and ill people also need professional nutritional guidance to meet deficiencies associated with the aging process or disease. The same is true for professional athletes and individuals working in strenuous physical and/or mental conditions. For the general population, the United States Department of Agriculture has designed the Food Guide Pyramid, illustrating the groups of foods and the daily-required variety of foods for optimum nutrition and health maintenance. Resources

USDA Food and Nutrition Information Center. Food Guide Pyramid. January 15, 2004 (May 20, 2004.) . U.S. Department of Agriculture. Nutrition.gov. January 15, 2004 (May 20, 2004). . ORGANIZATIONS

National Institute of Neurological Disorders and Stroke, P.O. Box 5801, Bethesda, MD 20824. (301) 496-5751 or (800) 352-9424. . American Dietetic Association. 120 South Riverside Plaza, Suite 2000, Chicago, IL 60606-6995. (800) 877-1600. [email protected]. .

Sandra Galeotti

Diffuse sclerosis see Schilder’s disease Diplopia see Visual disturbances

❙ Disc herniation Definition

Intervertebral discs are circular ring-like flat structures that function as cushions between two spinal vertebrae, allowing spinal flexibility and acting as shock absorbers. Each intervertebral disc contains a nucleus (center) surrounded by a sack of fibrocartilage (fibrous, connective tissue), rich in collagens (fibrous protein). A herniated disc occurs when the outer sack partially ruptures and the interior of the sack expands, pushing part of the disc into the spinal canal near to where the spinal cord and other nerve roots are located. This causes either chronic or acute pain in the back or in the neck, and movement restriction of the affected area due to pressure exerted on the spinal nerve roots. This condition is also known as a slipped disc, an intervertebral disc hernia, a herniated intervertebral disc, and a herniated nucleus pulposus.

Description

BOOKS

Champe, Pamela C., and Richard A. Harvey. Biochemistry, 2nd ed. Philadelphia: Lippincott Williams & Wilkins, 1994. Halliwell, Barry and Okezie I. Aruoma, (eds.) DNA and Free Radicals, 1st ed. London: Ellis Horwood Ltd., 1993. Mayhan, L. Kathleen, and Sylvia Escott-Stump. Krause’s Food, Nutrition and Diet Therapy. Philadelphia: W.B.Saunders, 2003. PERIODICALS

Ghani H., D. Stevens, J. Weiss, and R. Rosenbaum. “Vitamins and the Risk for Parkinson’s Disease.” Neurology (2002) 59: E8–E9. 290

OTHER

Intervertebral disc disease is among the most common causes of neck and back pain. Cervical disc herniations (in the neck region) are less common than lumbar (lower back) herniations. Lumbar disc herniations affect an estimated four out of five patients complaining of back pain. Several factors may contribute to a herniated disc, such as poor posture, work-related strain, traumatic injuries due to falls or blows in the back, improper weight lifting, obesity, and sport-related muscular strain. Disc herniation may also occur because of age-related degenerative processes that cause progressive loss of disc elasticity.

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Collagen The main supportive protein of cartilage, connective tissue, tendon, skin, and bone. Spinal cord The elongated nerve bundles that lie in the spinal canal and from which the spinal nerves emerge.

Other risk factors associated with disc hernias are lack of regular physical exercises, inadequate nutrition, smoking, and genetic factors.

Demographics Herniated disc is a common problem, with approximately one in 32, or 8.4 million people in the United States affected each year.

Causes and symptoms Degenerative disc disease, usually related to aging, is more common in the lumbar area, where much of the wear-and-tear of a lifetime of activity is exerted, resulting in chronic back pain. However, in the cervical area the disc degenerative process usually starts with a traumatic twisting of the disc space that leads to chronic inflammatory pain in the neck, and may result in arm pain and numbness. The degenerative process may also be associated with occupational repetitive movements such as those required in construction, farming, mining, and other professional activities where workers are required to handle heavy loads. Herniated discs sometimes cause pain that is incapacitating, and the condition accounts for a major cause of work disability and health care expense in the United States. Lumbar disc hernias are commonly associated with sciatica (inflammation of the sciatic nerve in the lower back) due to disc protrusion or herniation that compresses the spinal nerve root radiating to the femoral or sciatic nerve. A sensation of sharp, painful electric-like shock is felt during acute sciatica both in the back and along the involved limb. Other symptoms are a burning pain in the back, numbness or tingling sensation in the related leg, and weakness in one or both legs. Growing scientific evidence also points to genetic factors in disc herniation, especially in families with a history of predisposition to early-onset sciatica and disk herniation. The causation factor seems to be a mutation in one of the three genes (COL9A1, COL9A2, and COL9A3), which are related to the formation of collagen.

A clinical record of chronic back pain and progressive leg pain points to the possibility of a degenerative disc disease in progression; and physical palpation (examination by touch) by the physician may reveal whether a nerve root is affected. The straight leg-raising test (raising the leg straight, with no bend at the knee, until pain is experienced in the thigh, buttocks, and calf) can also point to nerve root irritation in the lumbosacral area due to herniated disc. X ray of the affected spinal area is the standard test for confirmation of a herniated disc. When surgery is being considered, other imaging tests are performed, such as a magnetic resonance imaging (MRI) scan or computed tomagraphy (CT) scan, for confirmation of the diagnosis.

Treatment team The orthopedist is the medical specialist often first consulted, and many orthopedic clinics offer the services of physical therapists whose interventions will be prescribed by the physician. In more severe cases, the intervention of a neurologist, neurosurgeon, or an orthopedic surgeon, along with a pain specialist may be required.

Treatment In most cases, conservative treatments such as overthe-counter painkillers, anti-inflammatory drugs, and muscle relaxants associated with a period of bed rest are enough to curb the acute phase. To prevent further acute pain, physical therapy and specific exercises may be recommended by the physician, along with the identification of poor postural habits and posture-correction exercises. However, in more severe cases where conservative treatment fails, further treatment may be necessary, such as injections with cortisone. Surgery is only a real necessity when a progressive loss of neurological function is experienced, leading, for instance, to bladder or bowel incontinence or limb paralysis. In cases of frequently recurrent acute pain, the person with a herniated disc chooses surgical intervention to decrease pain and improve quality of life.

Prognosis The vast majority of people (more than 90%) treated for herniated disc experience improvement with pain and mobility. About 5% of people who have experienced a herniated disc will eventually have recurring pain, and another 5% will experience a herniated disc at another vertebral site. Resources BOOKS

De Beeck, Rik Op, and Hermans Veerle. Research on WorkRelated Low Back Disorders. Brussels: Institute for

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Key Terms

Diagnosis

Dizziness

suffered from strokes may feel mild turning for periods of time. Mild turning may also be associated with multiple sclerosis, AIDS, or head trauma.

Occupational Safety and Health/European Agency for Safety and Health at Work, 2000. PERIODICALS

Humphries, Craig D., and Jason C. Eck. “Clinical Evaluation and Treatment Options for Herniated Lumbar Disc.” American Family Physician (1999): February 1, 575–587. OTHER

Herniated Disc—Factsheet. American Association of Neurological Surgeons. January 4, 2004 (March 18, 2004). . ORGANIZATIONS

National Institute of Arthritis and Musculoskeletal and Skin Diseases (NIAMS). 1 AMS Circle, Bethesda, MD 20892-3675. (301) 495-4484 or (877) 22-NIAMS; Fax: (301) 718-6366. [email protected]. .

Sandra Galeotti

❙ Dizziness Definition

Dizziness is a general term that describes sensations of imbalance and unsteadiness, such as vertigo, mild turning, imbalance, and near fainting or fainting. Feelings of dizziness stem from the vestibular system, which includes the brain and the parts of the inner ear that sense position and motion, coupled with sensory information from the eyes, skin, and muscle tension.

Description Because dizziness is a general term for a variety of feelings of instability, it spans a large range of symptoms. These symptoms range from the most dramatic, vertigo, to the least severe, imbalance. Included in these feelings is fainting, which results in a loss of consciousness. Vertigo is an acute feeling of violent rotation. People with vertigo often feel as if they are tilting or falling through space. Vertigo is most often caused by problems with the vestibular system of the inner ear. Symptoms can be brief, or may last for extended periods of time and may be accompanied by changes in pulse and blood pressure, perspiration, nausea, and a type of rapid eye movement called nystagmus. Mild turning is a less violent type of vertigo. People with mild turning are still able to function in normal daily routines. However, a feeling of turning may continue for weeks. Mild turning is usually a symptom of inner ear dysfunction. It may also result from transient ischemic attack, or a lack of blood flow to the brain. People who have 292

Imbalance is a feeling of instability or floating. It is associated with many general medical problems such as the flu or infection. Imbalance can also be associated with arthritis, especially in the neck, or another neurological problem. Fainting is a sudden loss of consciousness and near fainting is a feeling of extreme light-headedness with a sinking or falling feeling. Vision usually becomes hazy or dimmed and the extremities become weak. Both fainting and near fainting are caused by lack of blood flow to the brain. Anything that causes a rapid drop in blood pressure, such as a heart attack or an insulin reaction in a diabetic, can result in fainting or near fainting. Panic attacks that cause a person to exhale a lot of carbon dioxide can cause fainting or near fainting. Vestibular system The vestibular system is the sensory system located in the inner ear that helps the body to maintain balance. Balance in the human body is coordinated by the brainstem, which, with speed and precision, collects information from other parts of the brain and sensory organs throughout the body. It is the brainstem that sends neurological instructions to the muscles and joints. The sensory organs that play critical roles relaying information to the brainstem include the skin, eyes, muscles and joints, and the vestibular system in the inner ear. Dizziness may result with dysfunction in any of these components or in the nerves that connect them. Brain The cerebellum, which is responsible for coordination and the cerebral cortex, provides neurological information to the brainstem. For example, the cerebellum is the organ that informs the body how to shift weight when going down a flight of stairs and how to balance on a bicycle. These processes are accomplished without conscious thinking. In order to maintain balance, the brainstem depends on input from sensory organs including the eyes, muscles, joints, skin and ears. This information is relayed to the brainstem via the spinal cord. The combined neurological receptor system, which involves the brainstem, spinal cord, and sensory organs, is called the proprioceptive system. Proprioceptive dysfunction may result in dizziness, and people with problems with their proprioceptive system may fall often. Additionally, as people age, problems with proprioception become more common.

GALE ENCYCLOPEDIA OF NEUROLOGICAL DISORDERS

Auditory nerve A bundle of nerve fibers that carries hearing information between the cochlea the brain.

ance, and coordinating and controlling voluntary muscle movement.

Benign positional paroxysmal vertigo (BPPV) A common cause of dizziness thought to be caused by debris that has collected within a part of the inner ear.

Mèniére’s disease An inner ear disorder that can affect both hearing and balance, and can cause vertigo, hearing loss, along with ringing and a sensation of fullness in the ear.

Brainstem The part of the brain extending from the base to the spinal cord, responsible for controlling basic functions such as respiration and breathing.

Otolith organs Organs in the vestibular apparatus that sense horizontal and vertical movements of the head.

Cerebral cortex The surface gray matter of the cerebral hemispheres (cerebrum) of the brain, responsible for receiving sensory information, for conscious thought, and for movement.

Semicircular canals A set of three fluid-filled loops in the inner ear that are important to balance.

Cerebellum Area of the brain lying below and behind the cerebrum, responsible for maintaining bal-

Vestibular system The sensory system located in the inner ear that allows the body to maintain balance.

Sensory organs Visual information is of particular importance to maintaining balance. The visual systems most involved are the optokinetic and pursuit systems. The optokinetic system is the motor impulse responsible for moving the eyes when the head moves, so that the field of vision remains clear. The pursuit system allows a person to focus on a moving object while the head remains stationary. Both of these systems feed information about the person’s position relative to the surroundings to the brainstem. A specific type of eye movement called nystagmus, which is repetitive jerky movements of the eye, most often in the horizontal direction, may cause dizziness. Nystagmus may indicate that neurologic signals from the optokinetic or pursuit systems are not in agreement with the other balance information received by the brain. Sensory information from muscles, joints, and skin plays a key role in balance. The muscles and joints of the human body are lined with sensory receptors that send neurological information about the position of the body to the brainstem. For example, receptors in the neck muscles tell the brain which way the head is turned. The skin, in particular the skin of the feet and buttocks, is covered with pressure sensors that relay information to the brain regarding what part of the body is touching the ground. Peripheral vestibular system The ear, particularly the inner ear, plays a critical role in maintaining balance. The inner ear contains two major parts: the cochlea, which is mostly used for hearing, and the vestibular apparatus, also known as the peripheral

Vertigo Extreme dizziness.

vestibular system, which is important in balance. A set of channels connects the two parts of the ear and therefore any disease that affects hearing may also affect balance, and vice versa. The peripheral vestibular system consists of a series of canals and chambers, all of which are made of membranes. This membrane system is filled with a fluid called endolymph. The peripheral vestibular system is further embedded in the temporal bone of the skull. In the space between the temporal bone and the membranes of the peripheral vestibular system resides a second fluid called perilymph. Endolymph and perilymph each have a different chemical makeup consisting of varying concentrations of water, potassium, sodium, and other salts. Endolymph flows out of the peripheral vestiubular system into an endolymphatic sac and then diffuses through a membrane into the cerebrospinal fluid that bathes the brain. Perilymph flows out of the peripheral vestibular system and directly into the cerebrospinal fluid. When the flow pressures or chemical compositions of the endolymph and perilymph change, feelings of dizziness can occur. These types of changes may be related to Mèniére’s disease. The vestibular apparatus is made up of two types of sensory organs: otolith organs and semicircular canals. The otolith organs sense the direction of gravity, while the semicircular canals sense rotation and movement of the head. Two otolith organs in each ear are called the saccule and the utricle. The saccule is oriented in a vertical direction when a person is standing and, best senses vertical motion of the head. The utricle is nearly horizontal when a person is standing, so it best senses horizontal motion of

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Key Terms

Dizziness

the head. Each organ consists of calcium carbonate crystals embedded in a gel. Special hair-producing cells extend into the gel from below. As the head moves, gravity and inertia cause the crystals to bend the hairs, which are in contact with nerves. Information on the position and motion of the head is thus relayed to the brain. If the hairs or the crystals in the otolith organs are damaged, feelings of dizziness may result. In each ear, there are also three semicircular canals that lie on planes that are perpendicular to each other. The canals are connected together by a main chamber called a vestibule. The canals and the vestibule are filled with endolymph fluid. Near its connection to the vestibule, one end of each of the canals widens into a region called the ampulla. One side of the ampulla is lined with specialized sensory cells. These cells have hairlike structures that extend into a gelatinous structure called a cupula. As the head moves in a given plane, the endolymph inside the semicircular canal in that plane remains stationary due to inertia. The cupula, however, moves because it is attached to the head. This puts pressure on the cupula, which in turn moves the hairlike structures. The bending of the hairlike structures stimulates nerves, alerting the brain that the head is moving in a particular plane. By integrating information from all three planes in which the semicircular canals lie, the brain reconstructs the three-dimensional movement of the head. If information from one of the semicircular canals does not agree with that of another, or if the information generated by semicircular canals in one ear does not agree with the information produced by the other ear, feelings of dizziness may result. All of the signals from the peripheral vestibular system travel to the brain along the eighth cranial nerve, also called the vestibular nerve. Damage to this nerve, either through head trauma or the growth of tumors, can also cause feelings of dizziness. Neurological information from the semicircular canals seems be more important to the brain than information from the otolith structures. If the eighth cranial nerve on one side of the head is damaged, but the other side remains intact, the brain learns to compensate over time; however, the mechanics involved in this process are not well understood.

Demographics Dizziness is an extremely common symptom occurring in people of all ages, ethnicities, and socioeconomic backgrounds. Balance disorders increase with age, and by age 75, dizziness is one of the most common reasons for visiting a doctor. In the general population, dizziness is the third most common reason that patients visit doctors. According to the National Institutes of Health (NIH), about 42% of the population of the United States will complain of dizziness at some point in their lives. In the United 294

States, the cost of medical care for patients with symptoms of imbalance is estimated to be more than $1 billion per year. Diseases associated with dizziness Because it involves so many different parts of the body, the balance system may exhibit signs of dysfunction for a variety of reasons. Dizziness may be caused by problems with the central nervous system, the vestibular system, the sensory organs, including the eyes, muscles and joints, or more systemic disorders such as cardiovascular disease, bacterial and viral diseases, arthritis, blood disorders, medications, or psychological illnesses. Central nervous system dysfunction Any problem that affects the nerves leading to the brain from vestibular or sensory organs, the spinal cord, the cerebellum, the cerebral cortex, or the brainstem may result in dizziness. In particular, tumors that affect any of these organs are of concern. In addition, disorders that affect blood supply to the central nervous system, such as transient ischemic attacks, stroke, migraines, epilepsy, or multiple sclerosis, may result in feelings of dizziness. BRAIN TUMORS Although rare, acoustic neuroma is a benign tumor growing on the vestibulo-cochlear nerves, which reach from the inner ear to the brain. It may press as well on blood vessels that flow between the peripheral vestibular system and the brain. Symptoms included ringing in one ear, imbalance, and hearing loss. Distortion of words often becomes increased as the tumor grows and disturbs the nerve. Treatment requires surgical removal of the tumor, which nearly always returns the sense of balance to normal, although some residual hearing loss may occur. Other brain tumors may also cause feelings of dizziness. These include tumors that originate in the brain tissue, such as meningiomas (benign tumors) and gliomas (malignant tumors). Sometimes tumors from other parts of the body may metastasize in the brain and cause problems with balance. CEREBRAL ATROPHY Age causes atrophy (deterioration) of brain cells that may result in slight feelings of imbalance. More severe forms of dizziness may result from other neurological disorders. BLOOD SUPPLY DISORDERS If the blood flow and oxygenation to the cerebellum, cerebral cortex, or brainstem is not adequate, feelings of dizziness can result. Such symptoms can result from several types of disorders, including anemia, transient ischemic attacks (TIAs), and stroke. TIAs are temporary loss of blood supply to the brain, often caused by arteriosclerosis (hardening of the arteries). In addition to a brief period of dizziness or vertigo, symptoms include a transient episode of numbness on one side

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of the body, and slurred speech and/or lack of coordination. If the loss of blood supply to the brain is due to a blockage in one of the arteries in the neck, surgery may correct the problem. Strokes, or cerebrovascular accidents (CVA), occur in three major ways. A thrombotic stroke occurs when a fatty deposit forms a clot in an artery, blocking blood supply to the brain. An embolic stroke occurs when part of a clot from another part of the body breaks off and obstructs an artery leading to the brain. A hemorrhagic stroke occurs when blood vessels in the brain hemorrhage, leaving a blood clot in the brain. PERIPHERAL VESTIBULAR SYSTEM DYSFUNCTION

When balance problems are brief or intermittent, the peripheral vestibular system is usually the cause. Many different problems may be at the root of vestibular disorder. BENIGN PAROXYSMAL POSITIONAL VERTIGO (BPPV)

Benign paroxysmal positional vertigo occurs following an abrupt change in position of the head. Often, onset of vertigo occurs when patients roll from their back onto the side, and it usually subsides in less than a minute. BPPV can result from head trauma, degeneration of the peripheral vestibular system with age, infection of the respiratory tract, high blood pressure, or other cardiovascular diseases. Those who suffer from an infection of their vestibular system, causing severe vertigo that lasts up to several days, can develop BPPV any time within the next eight years. BPPV is also associated with migraine headaches. Two theories on the cause of BPPV currently exist. One suggests that BPPV will occur when the calcium carbonate crystals in the otolith organs (the saccule and the utiricle) are displaced and become lodged in the cupula of the semicircular canals due to head trauma, infection, or degeneration of the inner ear canals. This displacement will stimulate the nerves from the semicircular canals when the head rotates in a particular position, indicating to the brain that the person is spinning. However, the rest of the sensory organs in the body report that the body is stationary. This conflicting information produces vertigo. The calcium carbonate crystals dissolve after a brief time, and the symptom is rectified. The second theory suggests that cellular debris accumulates into a mass that moves around the semicircular canals, exerting pressure on the cupula and causing vertigo. When the mass dissolves, the symptoms subside. INNER EAR INFECTIONS Inner ear infection, or vestibular neuronitis, occurs some time after a person has suffered from a viral infection. Onset includes a violent attack of vertigo, including nausea, vomiting, and the inability to stand or walk. Symptoms subside in several days, although feelings of unsteadiness may continue for a week or more. A swelling of the vestibular nerve following a viral infection causes vestibular neuronitis.

Photographic representation of vertigo. (© 1993 J. S. Reid/Custom Medical Stock Photo. Reproduced by permission.)

Sometimes the inflammation can recur over several years. A viral infection affecting the inner ear, but not the vestibular nerve, is called viral labyrinthitis. Labyrinthitis can cause hearing loss, but all other symptoms are similar to vestibular neuronitis. Severe bacterial infections can also cause inflammation of the inner ear. These cases include risk of deafness, inflammation of the brain, and meningitis (inflammation of the membranes surrounding the brain and spinal cord). Otitis occurs when fluid accumulates in the middle ear, causing feelings of imbalance, mild turning, or vertigo. When the infection reaches the inner ear, the disease is called acute suppurative labyrinthitis. Treatment for any bacterial infection in the ear is critical to prevent long-term damage to hearing and balance organs. PERILYMPH FISTULA Perilymph fistulas are openings that occur between the middle ear and the inner ear. This allows a hole through which perilymph can flow, changing the pressure of perilymph flowing into the brain and causing dizziness. Fistulas often form as a result of head

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trauma or abrupt changes in pressure. Symptoms may also include hearing loss, ringing in the ears, coordination problems, nystagmus, and headaches. Most fistulas heal with time; however, in severe cases, surgical procedures are used to close the hole, using a tissue graft. MÈNIÉRE’S DISEASE In 1861, French physician Prosper Mèniére described Mèniére’s disease as having four particular symptoms: vertigo lasting for an hour or more, but less than 24 hours; ringing or buzzing sounds in the ear; feeling of pressure or fullness in the ear; and some hearing loss. Some people are affected in both ears; others just one ear. Onset of Mèniére’s may be related to stress, although not in all cases. Nystagmus is usually associated with the attacks.

Mèniére’s disease is thought to be caused by an accumulation of endolymph within the canals of the inner ear, a condition called endolymphatic hydrops. This causes produces a swelling in the canals containing endolymph, which puts pressure on the parts of the canals containing perilymph. The result affects both hearing and balance. In severe cases, it is feared that the endolymphatic compartments may burst, disrupting both the chemical and pressure balances between the two fluids. The cause of the accumulation of endolymph is unknown, although it can be related to trauma to the head, infection, degeneration of the inner ear, or some other regulatory mechanism. Syphilis is often associated with Mèniére’s disease, as are allergies and leukemia. Some suggest that Mèniére’s disease is an autoimmune dysfunction. There may be a genetic predisposition to Mèniére’s disease. Mèniére’s disease is usually treated with meclizine (Antivert), antihistamines, and sedatives. Diuretics can be used to rid the body of excess endolymph. Salt-free diets can also help to prevent the accumulation of fluid in the ears. Systemic disorders Dizziness may be a symptom of a disorder that affects the whole body, or systems within the body. Dizziness may also be the result of systemic toxicity to substances such as medications and drugs. POSTURAL HYPOTENSION The major symptom of postural hypotension, also called orthostasis, is low blood pressure. When a person stands up from a prone position, blood vessels in the legs and feet must constrict to force blood to the brain. When blood pressure is low, the blood vessels do not constrict quickly or with enough pressure and the result is a lag before blood reaches the brain, causing dizziness. Postural hypotension can be treated with an increase in fluid intake or with blood pressure medication.

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HEART CONDITIONS A variety of heart conditions can cause feelings of dizziness. In particular, arrhythmia, a dysfunction of the heart characterized by an irregular heartbeat, decreases blood supply to the brain in such a way as to cause balance problems. In most cases, symptoms of dizziness associated with arrhythmia result from problems with heart valves, such as narrowing of the aorta and mitral valve prolapse. INFECTIOUS DISEASES Influenza and flu-like diseases can cause dizziness, especially if accompanied by fever. The virus herpes zoster oticus causes painful blisters and shingles. If the virus attacks the facial nerve, it may result in vertigo. Several bacterial diseases can result in dizziness, including tuberculosis, syphilis, meningitis, or encephalitis. One of the major symptoms of Lyme disease, which is caused by infection of a microorganism resulting from a deer tick bite, is dizziness. BLOOD DISORDERS A variety of diseases of the blood result in feelings of dizziness. These diseases include anemia, or a depletion of iron in the blood, sicklecell anemia, leukemia, and polycythemia. DRUGS AND OTHER SUBSTANCES A variety of substances ingested systemically to prevent disorders of diseases can result in feelings of dizziness. In particular, overdose of aspirin and other anti-inflammatory drugs can cause problems with balance. Antibiotics taken for extended periods of time are also known to cause dizziness. Streptomycin is known to damage the vestibular system, if taken in large doses. Medicines that are used to treat high blood pressure can lower blood pressure so much as to cause feelings of light-headedness. Quinine, which is taken to treat malaria, can cause dizziness, as can antihistamines used to prevent allergy attacks. Chemotherapy drugs are well known to have various side effects, including dizziness. Alcohol, caffeine, and nicotine are also known to cause dizziness, when taken in large doses.

Diagnosis Because maintaining posture integrates so many different parts of the body, diagnosing the actual problem responsible for dizziness often requires a battery of tests. The cardiovascular system, the neurological system, and the vestibular system are all examined. Blood pressure is one of the most important cardiovascular measurements made to determine the cause of imbalance. Usually the physician will measure blood pressure and heart rate with the patient lying down, and then again after the patient stands up. If blood pressure drops significantly and the heart rate increases more than five beats per minute, this signals the existence of postural

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disorders of the vestibular organs, nystagmus will produce quick movements in the horizontal direction. People with neurologic disorders will show signs of nystagmus in the vertical direction or even in a circular pattern.

Neurological tests Because the central nervous system is integral to maintaining balance, neurological tests are often performed on patients with symptoms of dizziness. A test of mental status is often performed to ascertain that mental function is healthy. Physicians may test tendon reflexes to determine the status of peripheral and motor nerves, as well as spinal cord function. Nerves in different parts of the body may also be evaluated. In addition, physicians may test muscle strength and tone, coordination, and gait.

In most of the ENG tests, electrodes taped to the patient’s head record nystagmus as the patient is exposed to a variety of moving lights or patterns of stripes that stimulate the vestibular system. The patient may be asked to stand and lie in various positions for the tests. Also, included in the ENG is a caloric test in which warm water and cool water are circulated through the outer ear. This causes a slight expansion or contraction of the endolymph in the inner ear and simulates movement cues to the brain.

Neurologists may also perform a variety of computerized scans that determine if tumors or acoustic neuromas are present. These tests include magnetic resonance imaging (MRI), computerized tomography (CT), and electroencephalogram (EEG). Tests of the vestibular system Most often performed by a otolaryngologist, the battery of tests performed to determine the health of the vestibular system include the Dix-Halpike test, electrostagmography, hearing tests, rotation tests, and posturography. DIX-HALPIKE TEST The Dix-Halpike test, also called the Halpike test, is performed to determine if a patient suffers from benign paroxysmal positional vertigo (BPPV). The patient is seated and positioned so that his or her head hangs off the edge of the table when lying down. The patient’s head is moved 45 degrees in one direction. The patient is then asked to lie down, without moving his or her head. The same procedure will be repeated on the other side. If feelings of vertigo result from this movement, BPPV is usually diagnosed. ELECTRONYSTAGMOGRAPHY (ENG) Considered one of the most telling diagnostic tests to determine the cause of dizziness, electronystagmography consists of a series of evaluations that test the interactions between the vestibular organs and the eyes, also called the vestibulo-ocular reflex. Results from this test can inform the physician whether problems are caused by the vestibular system or by the central nervous system.

The most common diagnostic feature observed during ENG is nystagmus, an involuntary movement of the pupils that allows a person to maintain balance. In healthy persons, nystagmus consists of a slow movement in one direction in response to a change in the visual field and quick corrective movement in the other direction. In persons with

HEARING TESTS Because the cochlea and the vestibular organs are adjacent to one another, hearing dysfunction can often be related to problems with dizziness. Audiograms include tests for both hearing and interpreting sounds, and can determine whether or not problems exist in the middle ear, the inner ear, or the auditory nerve. ROTATION TESTS Rotation tests evaluate the vestibulo-ocular reflex and provide important information when the dysfunction is common to both ears. Electrodes are usually taped to the face to monitor eye movement, and the patient is placed in a chair. The chair rotates at different speeds through different arcs of a circle. The audiologist may also ask the patient to focus on different objects as the chair is rotated. POSTUROGRAPHY During posturography tests, a patient stands on a platform that measures how weight is distributed. During the test, the patient will close and open his or her eyes or look into a box with different visual stimuli. The platform is computer controlled so that it can gently tip forward or backward or from side to side. Posturography measures how much the patient sways or moves in response to the stimuli. This provides information on the function of the proprioceptive system, as well as the vestibular system.

Treatment If symptoms of dizziness are found to be associated with systemic diseases such as diabetes, hypotension, or other infectious diseases, or with neurological disorders, treatment for the dizziness is usually successful. In many patients, dizziness caused by vestibular dysfunction tends to dissipate with time and with little treatment. However, available and common treatments for vestibular problems include physical therapies, medications, and surgeries. In addition, low-salt diets, relaxation techniques, and psychological counseling may be used as treatment.

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hypotension. Dizziness in people suffering from diabetes or on blood pressure medicine may be caused by postural hypotension.

Dopamine receptor agonists

Exercises and therapy The physical therapies to decrease dizziness fall into two major groups. Compensation therapies help train the patient’s brain to rely on the sensory information it receives to maintain balance, and to ignore information from damaged organs. Exercises in a compensation program are designed to focus on the movements that cause dizziness so that the brain can adapt to these behaviors. In addition, exercises that teach the patient how to keep the eye movements separate from head movements and to practice balancing in various positions are used. Specific exercises aimed at relieving benign paroxysmal positional vertigo (BPPV), called canalith repositioning procedures, have recently been developed. By turning the head to one side and moving from a sitting to lying position in a certain sequence, BPPV can be quickly relieved. The movements in the canalith repositioning procedures are intended to move calcium carbonate crystals from the semicircular canals back to the utricle. The success rate with these exercises can be up to 90%. Medications A variety of medications are used to treat vertigo. These include vestibular suppressants, which seem to work by decreasing the rate of firing of nerve cells. Common vestibular suppressants are meclizine (Antivert, Bonine, and Vetrol). Also prescribed are anti-nausea medications such as promethazane (Phenergan) and antihistamines (Benadryl, Dramamine). For dizziness brought on by anxiety attacks, anti-anxiety drugs such as diazepam (Valium) and lorazepam (Ativan) may be used. These drugs all have side effects and are seldom prescribed for long periods of time. Surgery Surgery is usually the last step in the treatment of dizziness, only used after therapy and medications have failed. One of the more common surgical procedures for treating vestibular disorders is patching perilymph fistulas, or tears, at the tops of the semicircular canals. Surgery may also be used to drain excess fluid from the endolymphatic canals to relieve endolymphatic hydrops. Cutting the vestibular nerve just before it joins with the auditory nerve to form the eighth cranial nerve can also be performed to alleviate severe problems with dizziness. Finally, the entire labyrinth can be destroyed in a procedure called a labyrinthectomy, although this is usually only performed when hearing has been completely lost as well. Resources BOOKS

Blakely, Brian W., and Mary-Ellen Siegel. Feeling Dizzy: Understanding and Treating Dizziness, Vertigo, and Other Balance Disorders. New York: Macmillan USA, 1997.

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Olsen, Wayne, ed. Mayo Clinic on Hearing: Strategies for Managing Hearing Loss, Dizziness, and Other Ear Problems. Rochester, MN: Mayo Clinic Health Information, 2003. OTHER

“Vestibular Disorders: An Overview.” The Vestibular Disorders Association. November 3, 2003. (April 4, 2004). . “Equilibrium Pathologies.” Archives for Sensology and Neurootology in Science and Practice. January 2004 (April 4, 2004). . “Dizziness.” The Mayo Clinic. October 10, 2002 (April 4, 2004). . “Dizziness and Motion Sickness.” The American Academy of Otolaryngology and Head and Neck Surgery. January 30, 2004 (April 4, 2004). . “Balance, Dizziness and You.” National Institute on Deafness and other Communication Disorders. November 20, 2003 (April 4, 2004). . ORGANIZATIONS

Vestibular Disorders Association. P.O. Box 4467, Portland, OR 97208. (503) 229-7705 or (800) 837-8428. .

Juli M. Berwald, PhD

Donepezil see Cholinesterase inhibitors

❙ Dopamine receptor agonists Definition

Dopamine receptor agonists are a class of drugs with similar actions to dopamine, a neurotransmitter that occurs naturally in the brain. A neurotransmitter is a chemical that allows the movement of information from one nerve cell (neuron) across the gap between the adjacent neuron. Dopaminergic receptors are protein complexes on the surface of certain neurons of the sympathetic autonomic nervous system that bind to dopamine.

Purpose Dopamine stimulates the heart, increases the blood flow to the liver, spleen, kidneys, and other visceral organs, and controls muscle movements and motor coordination through an inhibitory action over stimuli response. Abnormal low levels of dopamine are associated with

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Description L-dopa (levodopa) is a precursor of dopamine, i.e., is converted into dopamine by the body. Levodopa thus increases dopamine levels in the motor areas of the central nervous system (CNS), especially in the initial stages of the disease. However, as the disease progresses, the drug loses its efficacy (effectiveness). When administered with carbidopa, levodopa’s effects are enhanced because carbidopa increases L-dopa transport to the brain and decreases its gastrointestinal metabolism. Therefore, two beneficial effects are achieved: better results with lower doses of levodopa (4–5 times lower doses than in L-dopa therapy alone); and reduction or prevention of levodopa side effects, such as nausea, anorexia, vomiting, rapid heart rate, low blood pressure, mood changes, anxiety, and depression. Bromocriptine mesylate is a derivative of ergotamine that inhibits the production of prolactin hormone by the pituitary gland. It is used in association with levodopa, in order to allow lower doses of the latter, especially in longterm therapy. Bromocriptine is also used to treat some menstrual disorders and infertility. This drug shows poor results in patients who do not respond to levodopa. Pergolide mesylate has an action similar to that of bromocriptine, also inhibiting prolactin secretion. Also used in Parkinson’s in association with L-dopa and carbidopa, pergolide is eliminated from the body through the kidneys. Cabergoline also inhibits prolactin secretion and is used to decrease abnormally high levels of this hormone, whether due to endocrine dysfunction or due to an

Key Terms Dopamine A neurotransmitter in the brain involved in regulating nerve impulses associated with muscle movement, blood pressure, mood, and memory. Dyskinesia Difficulty in moving, or a movement disorder. Neurotransmitter A chemical that is released during a nerve impulse that transmits information from one nerve cell to another.

existing pituitary tumor. The drug is also prescribed to regulate the menstrual cycle in cases of polycystic ovaries, and to control symptoms in Parkinson’s disease. Pramipexole and ropinirole are dopaminergic agonists that show good results in controlling Parkinson’s symptoms in patients still in the initial stages of the disease and not yet treated with L-dopa, thus postponing the need of levodopa administration to a later phase. They work as well in those patients with advanced Parkinson’s symptoms already taking levodopa.

Precautions Levodopa may worsen psychotic symptoms when administered to psychiatric patients and anti-psychotic drugs should not be taken with this medication. L-dopa is also contraindicated to patients with glaucoma, because it increases pressure within the eye. Patients with cardiac disorders must be carefully monitored during levodopa administration due to the risk of altered heart rhythms. Bromocriptine is contraindicated (not advised) for children under 15 years old, in pregnancy, severe cardiac disease, and severely decreased kidney or liver function. Alcoholic beverages are contraindicated during bromocriptine use as well as the administration of diuretics or anti-psychotic drugs. Psychiatric disorders may worsen with the administration of this drug. Pergolide is contraindicated in women who are breast-feeding or those with preexisting movement disorders or a psychotic condition. Patients with heart rhythm disturbances should be not take this medication. Cabergoline is not indicated in cases of severe or uncontrolled hypertension (high blood pressure) or for women who are breast-feeding, and requires careful monitoring in patients with significant kidney or liver dysfunction. Pregnant women who are at risk for eclampsia should not take this medication as well.

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tremors, muscular rigidity, low blood pressure, and low cardiac input. Therefore, dopamine and dopaminergic agonist drugs are administered to treat shock and congestive heart failure and to improve motor functions in patients with Parkinson’s disease and other movement disorders. The balance between two neurotransmitter levels, acetylcholine and dopamine, is essential for motor and fine movement coordination. The balance is frequently found altered in movement disorders, due to a dopamine deficiency that results in excessive stimulation of skeletal muscles. In Parkinson’s disease, either dopamine levels or the number of dopamine receptors are progressively decreased, resulting in tremors, slowness of movements, muscle rigidity, and poor posture and gait (manner of walking). Symptoms of Parkinson’s disease are treated with anticholinergic drugs and/or dopamine receptor agonists. Dopaminergic agonist drugs such as levodopa (Ldopa) along with carbidopa, bromocriptine mesylate, cabergoline, pergolide mesylate, pramipexole, and ropinirole hydrochloride are prescribed to treat the symptoms of Parkinson’s disease, either alone or in combinations.

Dysarthria

Pramipexole and ropinirole are eliminated through the kidneys, and the simultaneous use of medications that decrease kidney function (such as cimetidine) requires medical monitoring. Patients with reduced kidney function also require careful follow up and dosage adjustments.

Side effects Bromocriptine may cause gastrointestinal discomfort, constipation, abdominal cramps, fatigue, anxiety, urinary incontinence or retention, depression, insomnia, hypotension, anorexia (loss of appetite), and rapid heart rate. Pergolide side effects include dizziness when rising, increased heart rate, hallucinations, mood and personality disorders, ataxia (loss of coordination), muscle rigidity, blurred vision, anorexia, diarrhea, depression, insomnia, headache, confusion, numbness, gastritis, fluid retention, and swelling of the hands, face, and feet. Cabergoline side effects include gastrointestinal irritation, gases, abdominal pain, digestive difficulties, dry mouth, loss of appetite, depression, mood changes, anxiety, insomnia, depression, increased sex drive, low blood pressure, fatigue, body weight changes. Both pramipexole and ropinirole may cause hallucination (especially in elderly patients), dizziness and low blood pressure when rising, nausea, and gastrointestinal discomfort such as nausea and constipation. Pramipexole may also cause general swelling, fever, anorexia, and difficulty swallowing, decreased sex drive, amnesia and mental confusion, as well as insomnia and vision abnormalities. Ropinirole sometimes causes dizziness and fainting, with or without a slow heart rate.

Interactions Pyridoxine (vitamin B6) interferes with the transport of levodopa to the central nervous system by increasing its metabolism in the gastrointestinal tract. Dopamine antagonists (i.e., inhibitors of dopamine), such as metoclopramide and phenothiazines interfere with levodopa and other dopaminergic agonists, thus decreasing its effectiveness. The simultaneous concomitant use of phenelzine and dopamine agonists may induce severe high blood pressure. Resources BOOKS

Champe, Pamela C., and Richard A. Harvey, eds. Pharmacology, 2nd ed. Philadelphia, PA: Lippincott Williams & Wilkins, 2000. Weiner, William J., M.D. Parkinson’s Disease: A Complete Guide for Patients and Families. Baltimore: Johns Hopkins University Press, 2001.

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OTHER

“Dopamine Agonists.” WE MOVE. (April 23, 2004). “Pergolide.” Medline Plus. National Library of Medicine. (April 23, 2004). ORGANIZATIONS

National Parkinson Foundation. 1501 N.W. 9th Avenue, Bob Hope Research Center, Miami, Fl 33136-1494. (305) 2436666 or (800) 327-4545; Fax: (305) 243-5595. [email protected]. .

Sandra Galeotti

Dural sinuses see Cerebral circulation

❙ Dysarthria Definition

Dysarthria is a speech diagnostic term that can be used to classify various types of neuromuscular speech disturbances. Dysarthria results from notable degrees of one or more abnormalities involving speech musculature, including weakness, paralysis, incoordination, sensory deprivation, exaggerated reflex patterns, uncontrollable movement activities, and excess or reduced tone. Generally speaking, the dysarthrias are considered motor speech disorders because speaking difficulties are largely due to breakdowns in movement control of one or more muscle groups that compose the speech mechanism. The name of each dysarthria subtype is partially derived from the basic characteristics of the overlying movement disturbances. Notably, normal speech production involves the integration and coordination of five primary physiological subsystems: respiration (breath support); phonation (voice production); articulation (pronunciation of words); resonation (nasal versus oral voice quality); and prosody (rate, rhythm, and inflection patterns of speech).

Description The pioneering works of Darley, Aronson, and Brown in 1975 led to the general model of dysarthria classification that continues to be used to date. These clinical researchers from the Mayo Clinic studied individuals with different neurological disorders for the primary purpose of identifying and describing in detail the various speech

GALE ENCYCLOPEDIA OF NEUROLOGICAL DISORDERS

Demographics There are no known figures regarding the overall incidence of the various dysarthrias in the general population. Moreover, because numerous possible neuropathological conditions can result in dysarthria, it is unproductive to speculate about either the specific or overall demographics of this multi-varied disorder.

Causes and symptoms Spastic dysarthria Spastic dysarthria is caused by damage to the primary voluntary motor pathways, which originate in the frontal lobes of the brain and descend to the brainstem and spinal cord. These central tracts constitute the pyramidal or upper motor neuron (UMN) system. Virtually all individuals with spastic dysarthria present with a broad spectrum of speech disturbances, including: • abnormally excessive nasal speech quality • imprecise articulation behaviors such as slurred sound productions and periods of speech unintelligibility • slow-labored rate of speech • strained or strangled voice quality • limited vocal pitch and loudness range and control • incoordinated, shallow, forced, uncontrolled, and overall disruptive speech breathing patterns Individuals with spastic dysarthria often suffer from co-occurring weakness and paralysis of all four limbs. This occurs because the nerve tracts that supply movement control to these structures run in close parallel to those that regulate muscles of the speech mechanism, thereby making them equally susceptible to damage. The specific combination and severity of these features tend to vary from person to person based on the extent of associated UMN damage. In general, people with spastic dysarthria struggle with these speech difficulties because of widespread involvement of the tongue, lip, jaw, soft palate, voice box, and respiratory musculature. Problems with emotional breakdowns, such as unprovoked crying and laughing, also occur in many cases, due to uncontrolled releases of primitive reflexes and behaviors normally regulated, in

part, by a mature and healthy UMN system. Finally, swallowing difficulties, known as dysphagia, are not uncommon in this population, because of underlying weakness and paralysis of the tongue and throat wall muscles. The most common causes of spastic dysarthria include spastic cerebral palsy, multiple sclerosis, amyotrophic lateral sclerosis (ALS, or Lou Gehrig’s disease), multiple strokes, and closed head injuries (particularly those that cause damage to the brainstem where the UMN tracts converge on the way to nerves that directly connect with the various muscles of the head, neck, limbs, and girdle). Unilateral upper motor neuron (UMN) dysarthria Unilateral UMN dysarthria is caused by damage to either the left or right UMN tract, anywhere along its course to the brainstem and spinal cord. The individual with this diagnosis generally presents with mild to moderate weakness and paralysis of the lower face, tongue, arm, and leg on the side of the body opposite the damaged UMN tract. The hemiplegia may necessitate use of a cane or wheelchair, and the facial and tongue musculature disturbances usually only result in mild speech production and swallowing difficulties because the unimpaired opposite half of the lips and tongue often compensate well for this unilateral problem. Speech breathing and inflection patterns, voice characteristics, and nasal resonance features are not typically abnormal in the individual with unilateral UMN dysarthria. However, it is not uncommon for this person to suffer from a significant language processing disorder (i.e., aphasia) and/or apraxia in which the brain damage also involves areas of the cortex that normally regulate motor programming and language formulation abilities. The most common causes of this dysarthria subtype are cerebral vascular accidents (i.e., strokes) and mild-tomoderate head injuries. Ataxic dysarthria Ataxic dysarthria is caused by damage to the cerebellum or its connections to the cerebral cortex or brainstem. This component of the central nervous system is chiefly responsible for regulating the force, timing, rhythm, speed, and overall coordination of all bodily movements. When the cerebellum is damaged the affected person may exhibit drunk-like motor patterns, characterized by a wide-based and reeling gait and slurred articulation patterns with intermittently explosive voice pitch and loudness outbursts. During purposeful movement efforts, this individual often suffers from intention tremors, which cause under- or overshooting of the intended target.

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problems that they exhibited. These analyses helped to formulate predictable subtypes of speech abnormalities in individuals with specific kinds of neuropathologies. Besides the six primary forms of dysarthria identified, a seventh type has been added to the differential diagnostic scheme in the past decade. The seven dysarthria subtypes are spastic, unilateral upper motor neuron, ataxic, hypokinetic, hyperkinetic, flaccid, and mixed.

Dysarthria A speech therapist helps a young boy sound out words. (© Photo Researchers. Reproduced by permission.)

However, this shaking phenomenon tends to disappear at rest. Swallowing is not usually disturbed.

tremors, and incoordination of the tongue, lip, jaw, and voice box musculature.

The most common causes of ataxia include cerebral palsy, multiple sclerosis, and closed head injuries.

Because the most common cause of hypokinetic dysarthria is Parkinson’s disease, patients with these types of speech problems also exhibit numerous trunk and limb disturbances such as rest tremors of the hands, stooped posture, shuffling gait, and mask-like facial expressions due to involvement of associated body musculature. Swallowing difficulties may co-occur.

Hypokinetic dysarthria Hypokinetic dysarthria is caused by damage to the upper brainstem in a region that is richly composed of darkly pigmented (nigra) nerve cells. These neurons contain the neurochemical agent dopamine, which helps regulate muscle tone and smooth and complete bodily movements. When various speech muscles are involved, numerous communication deficits occur, including imprecise articulation of sounds, harsh-hoarse voice quality, and abnormal bursts of speech that sound like the individual is tripping over his or her tongue. These common dysarthric features are the result of widespread rigidity (i.e., stiffness and limited range of motion [hypokinesia]),

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Hyperkinetic dysarthria Hyperkinetic dysarthria is generally caused by damage to nerve pathways and centers within the depths of the brain (subcortex) known as the basal ganglia. These integrated central nervous system components form complex feedback loops between one another and the cerebral cortex. The basal ganglia are largely responsible for helping to maintain posture, muscle tone, bodily adjustments, and

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Patients with Huntington’s disease and tic disorders frequently exhibit the quick and jerky forms of movement abnormalities. The slow, writhing, and twisting movement disorders are usually observed in patients with histories of dystonia, athetosis, torticolis, and dyskinesia. In fact, spasmodic dysphonia, characterized by strainedstrangled or abnormally breathy vocal quality and episodes of periodic arrests of voice, is a form of hyperkinetic dysarthria in that dystonia involves the vocal cords. Tremors are common in patients with essential (organic) tremor disorders. In general, when tongue, lip, and jaw muscles are afflicted by such breakdowns, the articulation of speech sounds is inconsistent and imprecise, voice is hoarse-harsh in quality, the rhythm of speech is flat and irregular, and breathing patterns are sudden, forced, and shallow. All of these disturbances contribute in total to variable, but often-marked degrees of speech unintelligibility in these clinical populations. Whereas in most cases the underlying cause of muscle hyperactivity is associated with one of the above listed disease-specific entities, occasionally severe head injuries and deep brain tumors can result in any of these types of movement control disorders. Swallowing difficulties can be a significant problem for these types of patients. Flaccid dysarthria Flaccid dysarthria is caused by damage to nerves that emerge from the brainstem (cranial) or spinal cord and travel directly to muscles that are involved in speech production. These nerves are generically referred to as lower motor neurons. Cranial nerves V, VII, X, and XII are of great importance because they supply the chief muscles of speech production, namely, the jaw, lips, voice box and palate, and tongue, respectively. The cervical spinal nerves innervate the diaphragm, and the thoracic spinal nerves stimulate the chest and abdominal wall muscles, all of which are involved in speech breathing activities. The types of neuromuscular problems that arise as a result of injuries to these nerves depend upon which and how many nerves are disturbed. In general, the types of abnormal muscle signs occurring in patients with damage to lower motor neurons include paralysis, weakness, reduced speed of movement, depressed tactile feedback, limited reflex behaviors, and atrophy or shrinkage of muscle tissue.

Analyses of the electrical activity of involved muscles using needle electrodes frequently reveal disturbed firing patterns or twitch-like behaviors known as fasciculations. In a structure like the tongue, which is not covered with thick overlying skin, fasciculations can sometimes be evident by shining a flashlight on the surface at rest. This pathologic feature is an important differential diagnostic sign of damage to the cranial nerve XII. Patients with limited lower motor neuron damage usually exhibit less severe flaccid dysarthria than those with more widespread damage. Additionally, the actual nerves that are damaged dictate the specific types of speech difficulties that may occur. For example, if a focal lesion involves only the cranial nerve VII, as in Bell’s palsy, only the lip musculature will be weakened. The result in this case usually produces minimal dysarthria. However, damage to multiple cranial nerves, as often occurs in certain degenerative conditions like Lou Gehrig’s disease, will likely cause severe speech difficulties. The most common speech signs observed in patients with flaccid dysarthria, regardless of the cause or severity, include articulation imprecision, hypernasal voice, hoarse and breathy vocal quality, and slow-labored speech rate. Brain stem strokes, tumors on the brain stem or along the course of the cranial or spinal nerves, muscular dystrophy, and general injuries to these nerves as a result of head trauma or surgical complications are among the most frequent causes of flaccid dysarthria. If spinal nerves that supply the limbs are also damaged, as may be the case in some of these clinical populations, co-occurring paralysis of these structures is likely to complicate the rehabilitation program. Swallowing problems may occur in some cases, depending upon which and how many cranial nerves are involved. Mixed dysarthria Mixed dysarthria is caused by simultaneous damage to two or more primary motor components of the nervous system, such as the combined upper and lower motor neuron lesions that typically occur in Lou Gehrig’s disease, or the co-occurring degeneration of the upper motor neuron and cerebellum pathways seen in patients with multiple sclerosis. In the first example, the patient usually suffers from mixed spastic-flaccid dysarthria. In the second case, the MS patient often presents with mixed spastic-ataxic dysarthria. The exact mixture of neurological damage governs the characteristic speech (and overall body) musculature difficulties. It is not uncommon for severe head injuries to cause multi-focal nervous system lesions and nonspecific mixed dysarthrias. Many such patients also struggle with limb and trunk motor problems, as well as coexisting swallowing, cognitive, language, perceptual, and psychosocial

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overall stability during gross voluntary movement patterns. Damage to these structures and their circuitry generally produces two different types of symptoms, depending upon the site(s) of injury: increased muscle tone and very slow movement, known as rigidity, as seen in patients with Parkinson’s disease, or involuntary, excessive, and uncontrollable quick-jerky, slow-twisting, or trembling limb and speech musculature behaviors.

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deficits that worsen their underlying motor speech problems and complicate the rehabilitation course. The mixture may be of two or more of the previously described singleentity dysarthrias.

Diagnosis In addition to clinical examinations, many dysarthric patients will need to submit to various laboratory studies for a thorough appraisal of the possible underlying causes, areas of brain damage, and overall prospects for improvement with appropriate treatment. Such testing might include: • computed tomography (CT) or magnetic resonance imaging (MRI) scans of the head, neck, and/or chest • skull x rays • arteriography (imaging of arterial flow dynamics) • spinal tap for cerebral spinal fluid analysis

or more of these problems may be evident in the speech profiles of individuals with different forms of dysarthria.

Treatment team The rehabilitation team for an individual with dysarthria often varies, depending on the severity and cause of the dysarthria and the extent of associated limb and trunk musculature disabilities and co-occurring language, cognitive, and psychosocial deficits. In general, those individuals with multi-system breakdowns require a more complex array of team constituents than those who have more focal or mild problems. Most teams consist of the clinical neurologist, speech-language pathologist, physical therapist, occupational therapist, neuropsychologist, nurse practitioner, and social worker. In school-age patients, teachers and guidance counselors will also play very important roles in the treatment program. Naturally, the role of the speech pathologist is usually most critical in the communication treatment plan for dysarthric patients.

• electroencephalography (EEG)

Treatment

• electromyography (EMG) • videoendosocopy of the vocal cords and soft palate • pulmonary function studies • videofluoroscopic examinations of swallowing proficiency • speech aerodynamic and acoustic analyses These diagnostic tests require the cooperation of many different clinical practitioners from various fields of study. Familiarity with the variable speech subsystem abnormalities exhibited by dysarthric patients is indispensable to differential diagnosis. Additionally, because dysarthria is only a speech diagnostic term, and the underlying cause is some form of neurological problem, a medical examination, usually performed by a clinical neurologist, is critical both to the overall diagnosis in any given case and for effective treatment recommendations. Family members and friends can, however, facilitate this process by cursory investigations of the speech difficulties prior to visiting with diagnosticians for formal testing. This preparatory process may involve having the patient perform several physiologic tasks, as well as noting any generalized walking, balance, and limb coordination difficulties exhibited by the affected individual. If the possible cause is understood from the outset, it may help pinpoint the speech diagnosis. The individual can be engaged in general conversation to judge overall speech intelligibility. The listener can listen for signs of poor pronunciation of sounds, excessively nasal voice, hoarseness or strained vocal quality, breath support difficulties, and limited pitch and loudness inflection patterns. Any one 304

Physical and occupational therapists focus on improving limb and trunk coordination, balance, and range of motion, particularly in relation to daily living functions such as walking, self-dressing, and feeding. Neuropsychologists often facilitate memory strategies, perceptual processes, and overall organizational skills required in various work-related settings and daily social circumstances. The administration of certain medications, daily health care and personal hygiene needs, and general tracheostomy care and feeding-tube monitoring may be indicated. The speech pathologist must design specific speech musculature exercises to improve the strength, tone, range of motion, coordination, and speed of integrated tongue, lip, jaw, and vocal musculature contractions. These general objectives are often achieved following a hierarchy of exercises that may require two or more sessions of therapy per week. In some cases, when oral speech skills fail to improve with both speech and non-speech exercises, use of an alternative or augmentative communication system is required, such as computerized speech synthesizers and/or form or picture boards. These tools are most useful for those patients who possess at least some control of an upper limb to activate a keyboard or point to a picture. In very severely affected patients, a head pointer may be devised so that head movements meet these objectives.

Prognosis The prognosis for speech improvement in any individual with dysarthria usually depends on the severity of the problem and the underlying cause. If the speech difficulties are mild to moderate, and the cause has been

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Special concerns Depending on the cause and the severity of the dysarthria, and any coexisting motor, language, cognitive, intellectual, and psychosocial deficits, the affected individual may require many different methods of care. Formal nursing or group home settings are sometimes necessary for those individuals who are not self-sufficient or who lack home care assistance and supervision. Special education classes may be required in those cases with associated learning disabilities. Structural modifications of a wheelchair to facilitate upright head posturing and abdominal support during speech breathing efforts may be helpful for some patients, and construction of ramps in the home may also be necessary to accommodate wheelchair mobility requirements. Arrangements for use of a bell or light switch activator may be indispensable to certain patients who cannot verbally, or otherwise, get the attention of caregivers. Resources BOOKS

Darley, F. L., A. E. Aronson, and J. R. Brown. Motor Speech Disorders. Philadelphia: W. B. Saunders, Company, 1975. Duffy, J. R. Motor Speech Disorders: Substrates, Differential Diagnosis, and Management. St. Louis: Mosby, 1995. Dworkin, J. P. Motor Speech Disorders: A Treatment Guide. St. Louis: Mosby, 1991. Dworkin, J. P., and R. A. Cullata. Dworkin-Culatta Oral Mechanism Examination and Treatment System. Farmington Hills, MI: Edgewood Press, 1996. Robin, D. A., K. M. Yorkston, and D. R. Beukelman. Disorders of Motor Speech. Baltimore, MD: Paul H. Brookes Publishing, 1996. Vogel, D., and M. P. Cannito. Treating Disordered Speech Motor Control (2nd Ed). Austin, TX: Pro-Ed, 2001. Yorkston, K., D. R. Beukelman, E. Strand, and K. Bell. Management of Motor Speech Disorders in Children. Austin, TX: Pro-Ed, 1999. ORGANIZATIONS

Department of Otolaryngology, Head and Neck Surgery, Wayne State University, 5E-UHC, Detroit, MI 48331. (313) 745-8648. [email protected].

James Paul Dworkin, PhD

Dysautonomia see Autonomic dysfunction

❙ Dysesthesias Definition

The word dysesthesias is derived from the Greek “dys,” which means “bad,” and “aesthesis,” which means “sensation.” Thus, dysesthesias are “bad sensations” and the word refers to pain or uncomfortable sensations, often described as burning, tingling, or numbness.

Description Dysesthesias is a symptom of pain or abnormal sensation(s) that typically cause hyperesthesia, paresthesiae, or peripheral sensory neuropathy. Dysesthesias can be due to lesions (an abnormal change) in sensory nerves and sensory pathways in the central nervous system (CNS, consisting of the brain and the spinal cord). The pain or abnormal sensations in dysesthesias is often described as painful feelings of tingling, burning, or numbness. Dysesthesias can simply be described as a burning pain that is worse where touch sensation is poorest. Dysesthesias can also be caused by lesions in peripheral nerves (the peripheral nervous system, or PNS, which consists of nerves that are outside the brain or spinal cord). Peripheral nerves travel to muscles and organs providing a nerve supply. Dysesthesias due to a lesion in the PNS usually occurs below the level of the lesion. There is a broad spectrum of diseases, disorders, and medications that cause dysesthesias. There are two broad categories of dysesthesias called paresthesiae and peripheral sensory neuropathy. Some of the common causes of dysesthesias within these categories will be considered.

Paresthesias Paresthesias (abnormal neurological sensations that include numbness, tingling, burning, prickling, and increased sensitivity, or hyperesthesia) can include several conditions such as carpal tunnel syndrome, thoracic outlet syndrome, multiple sclerosis, strokes (cerebrovascular accidents), Guillain-Barré syndrome, transverse myelitis, and compartment syndrome/Volkmann’s contracture.

Carpal tunnel syndrome Carpal tunnel syndrome is caused by entrapment of the median nerve at the wrist. There is limited available space for the median nerve. There is a disease process (i.e. osteoarthritis) that entraps the nerve. Symptoms include paresthesiae of the first three fingers usually present overnight and typically relieved by shaking or elevating the hands. Symptoms progress to sensory loss and weakness of muscles. Treatment usually includes overnight splinting, diuretics (to reduce swelling), or surgery.

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treated successfully through proper medical avenues and is non-progressive, the prognosis for notable improvements with good speech therapy is often very good. However, in the case of severe dysarthria, with a medically uncontrollable or progressively deteriorating etiology, the prognosis for significant gains, even with the best therapeutic programs possible, is almost always very guarded.

Dysesthesias

Thoracic outlet syndrome Thoracic outlet syndrome is a condition caused by compression of nerves (and blood vessels) located between the armpit and the base of the neck. The neurologic symptoms associated with thoracic outlet syndrome include dysesthesias (numbness and tingling), weakness, and fatigability. The damage occurs in nerves leaving the spinal cord located behind the neck. Symptoms worsen with arm elevation above the level of the shoulder. Approximately 50% of persons affected report a history of a single traumatic event (i.e., motor vehicle accident) that caused a neck injury.

Multiple sclerosis/transverse myelitis Multiple Sclerosis is an inflammatory process that involves white matter. There is focal neurologic deficit which can progress. The condition can go in remission but other attacks usually occur causing neurologic deficits. Transverse myelitis (usually associated with an inflammatory process) can cause back pain, leg weakness, and sensory disturbance. Transverse myelitis can occur after viral infections or may even occur as a feature of multiple sclerosis.

Stroke (cerebrovascular accident) There are two major arteries implicated with stroke. These include the carotid arteries (in the neck and travels into the brain) and the basilar artery (an artery located in the base of the skull). The dysesthesias associated with carotid artery stroke consists of tingling and numbness on one side of the body. Stroke associated with the basilar artery can cause dysesthesias (tingling or numbness) in the cheeks, mouth, or gums.

Guillain-Barré syndrome Guillain-Barré syndrome (also called acute inflammatory demyelinating polyneuropathy) is an immune mediated disorder that follows some infectious process (such as infectious mononucleosis, herpes viruses, cytomegalovirus, and mycoplasma), and is the most frequent caused of acute flaccid paralysis throughout the world. Initial symptoms consist of “pins-and-needles sensations” in the feet, lower back pain, and weakness (which develop within hours or days). Weakness is prominent in the legs. Progression of symptoms can occur abruptly and patients may have serious involvement of nerves responsible for respiration and swallowing, which may be life-threatening. The condition is serious and could cause rapid deterioration. Patients usually require hospitalization and treatment with high doses of human immunoglobulin and plasmapheresis (exchange of patient’s plasma for the protein called albumin).

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Key Terms HIV Human immunodeficiency virus, which causes AIDS. Lacinating pain Piercing, stabbing, or darting pain. Lymphocytic meningitis Benign infection of brain coverings that protect the brain. Radiculoneuritis Inflammation of a spinal nerve. Rodenticide Chemical that kills rodents.

Compartment syndrome/Volkmann contracture Compartment syndrome refers to any condition that causes a decrease in compartment size or increased compartment pressure. Compartment syndromes can be caused by crush injuries, internal bleeding, fractures, snake bites, burns, and excessive exercise. If a compartment (or area) is injured (i.e., a crushing injury to hand), the trauma will decrease the normal area of the hand (due to bleeding). This results in an increase in compartmental pressure which could impair blood flow to the area, causing irreversible tissue ischemia (tissue death). Compartment syndrome can occur from injuries to the upper extremity which can affect the forearm and hand since these areas have naturally occurring compartments made by anatomical structures such as muscle. Excessive swelling due to traumatic injury can cause nerves and blood vessels to be compartmentalized (in a sense, crushed against) muscle from abnormal swelling or internal bleeding. If left untreated the dead muscle and nerve tissue is replaced with fibrous tissue causing a Volkmann ischemic contracture (contractures of fingers or in severe cases the forearm). In severe cases there is a loss of nerve tissue. Damage shows signs in 30 minutes and measurable functional loss after 12 to 24 hours.

Peripheral neuropathy Peripheral neuropathies are conditions that cause injury to nerves that supply sensation to the legs and arms. This category of dysesthesias can include conditions such as amyloidosis, Charcot-Marie-Tooth syndrome, diabetes, leprosy, syphilis, and Lyme disease.

Amyloid neuropathies/hereditary neuropathies There are several types of amyloid neuropathies, and they are all associated with diseases that deposit a protein (amyloid) in nerves and even other tissues (like blood vessels). Sensory nerves are damaged causing dysesthesias.

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Diabetes (metabolic neuropathy) The most frequent neuropathy world wide is diabetes. Peripheral neuropathy can be detected in approximately 70% of long-term diabetics. The cause of nerve involvement is unclear, but it is thought that a faulty mechanism (deleterious to nerve cells) is related to high blood glucose levels. The symptoms are insidious and typically include dysesthesias evoked by regular activity (i.e., bothersome tingling of toes under bed sheets). The pain can be throbbing or it may be a continuous burning type of dysesthesias. Additionally, person may describe abrupt, quick “lightning” pains which may affect the feet and legs.

Leprous neuropathy Leprosy is an infectious disease transmitted by a bacterium called Mycobacterium leprae. The World Health Organization (WHO) estimates that there are 2.5 million persons affected by leprosy. The organism proliferates in coolest regions of skin (i.e., ears, face, fingers), causing a selective loss of pain sensation (dysesthesias) in cold areas of skin.

Neurosyphilis Neurosyphilis refers to a disease caused by untreated syphilis infection that invades the central nervous system years after initial infection. In the United States the number of cases of neurosyphilis has risen from 10,000 in 1956 to over 50,000 in 1990. Approximately 28% of patients have ataxia, 23% have stroke, and 10% of affected persons describe “lightning” pains. Additionally 10% have headaches and 36% have cranial neuropathy. Treatment attempts include antimicrobial therapy.

symptoms such as lymphocytic meningitis, cranial neuropathy (especially facial nerve palsy), and radiculoneuritis. Patients may also have musculoskeletal pain that includes muscle pain (myalgia) and joint aches (arthralgia). Late symptoms include encephalopathy, sleep disturbances, fatigue, and personality changes.

Other causes of dysesthesias Toxic neuropathies Toxic neuropathies can occur due to medications (used to treat illnesses), metal exposures, substance abuse, and exposure to industrial poisons/chemicals. For drug (medications) or chemical exposure induced neuropathies the cause (mechanism of damage) is usually obscure. Medications that can cause neuropathies include (but are not limited to) antivirals, chloramphenicol (antibiotic), cisplatin (anticancer), ethambutol (antitubercolosis), hydralazine (antihypertensive), isoniazid (antitubercolosis), metronidazole (antifungal), phenytoin (antiepileptic), pyridoxine (vitamin B-6), gold therapy, and vincristine/vinblastin (anticancer) therapy. Metals that can cause neuropathies include arsenic, lead, mercury, and thallium (a metal in rodenticides such as Gizmo mouse killer). Heavy metals such as lead found in lead-based paint in the automobile industry and manufacture of storage batteries and printing can cause neuropathies. Lead neuropathy can occur due to drinking bootleg whiskey distilled in lead pipes, or hand mixing of lead-based paints by artists. Occupational exposure in farming to arseniccontaining sprays, pesticides, and weed killers can cause arsenic neuropathy. Accidental ingestion of arseniccontaining rodenticides can cause arsenic neuropathy. Chemical abuse with alcohol or by glue or nitrous oxide inhalation can cause neuropathies. Severe peripheral neuropathies can result from exposure to household and industrial chemicals. Thallium neuropathy Thallium neuropathy can occur in manufacturers of optic glass, industrial diamonds, and prisms. Thallium is also used as an additive in internal combustion engines. Accidental ingestion of thallium and subsequent neuropathy also occurs with rodent killer substances (rodenticides).

Lyme disease (Boreliosis) Lyme disease is an infection transmitted by an arthropod (a tick which harbors the infectious bacterium called Borrelia burdorferi). The bacteria can be transmitted to a human by the bite of infected deer ticks, and in 2002 caused 23,000 infections in the United States. After the initial symptoms (“bulls-eye” rash, fever, fatigue, muscle aches, and joint aches), early disease can cause neurologic

HIV infection Before development of AIDS, persons with HIV infection can develop chronic inflammatory peripheral neuropathy. However, the most prevalent neuropathy associated with HIV infection is sensory neuropathy of AIDS, which causes pain on the soles of the feet and discomfort when walking. The pain is intense and affected

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These disorders are inherited, occur in midlife, and represent the most relevant inherited neurologic diseases. These include Charcot-Marie-Tooth disease and amyloid neuropathies. Charcot-Marie-Tooth disease refers to inherited disease that causes nerve degeneration usually in the second to fourth decades of life. Patients exhibit impairment of sensory function, and the nerves of the toes and feet are affected (can lead to foot drop.)

Dysesthesias

persons may have motor impairment. The condition is caused by degeneration of sensory nerve fibers. Shingles Another condition called herpes zoster or shingles (caused by the varicella zoster virus which causes chicken pox) can cause a latent nerve neuropathy with localized cutaneous eruptions during periods of reactivation. There are over 500,000 cases of shingles estimated to occur annually in the United States. The abnormal skin sensations are localized and range from itching to tingling to severe pain. Treatment typically includes antiviral medications. Pain can persist for months or even years. Bell’s palsy The cause of Bell’s palsy is unclear. It is thought to be due to an infectious process, possibly viral, that involves a nerve in the face called the facial nerve. Pain is often sudden and patients often describe a “numbing of the face” sensation. Biological toxins The ingestion of a certain fish (ciguatera) and some shellfish can be the cause of acute peripheral neuropathy (paresthesia). The typical causes among ciguatera include red snapper and barracuda from waters in the West Indies, Florida and Hawaii. Shellfish, clams scallops and mussels from the waters of Alaska, New England and the west coast are also causative biologic toxins. The neuropathy is followed after a few hours from the initial symptoms of nausea and vomiting. Paresthesiae occurs around the face and spreads to limbs. The problem can quickly progress to respiratory paralysis (paralysis of the muscles responsible for respiration) which could be a life-threatening condition. Vitamin Deficiency Neuropathy can result due to vitamin deficiencies such as vitamin B-12, vitamin B-1 and vitamin E. Vitamin B-12 deficiency can cause dysesthesias (sensation of “pins-and-needles” and numbness) in the feet and hands. Usually patients are diagnosed since they have a blood disorder called macrocytic megaloblastic anemia. Patients who have a bowel problem called malabsorption may loose ingested fat substances in the feces undigested, causing a loss of essential vitamins and nutrients. Fat containing molecules like vitamin E may be lost causing a neuropathy with symptoms similar to vitamin B-12 deficiency. Vitamin B-1 deficiency can likely occur due to alcoholism. The neuropathy is mostly sensory and patients describe a painful hypersensitivity of the feet. In advanced cases there may be weakness in the limbs or even paralysis leading to wrist drop or foot drop. 308

Nerve root compression Radiculopathy, commonly caused by disk herniation (nerve root compression) is generally accompanied by muscle weakness, sensory loss and absent tendon reflexes. Herpes zoster radiculopathy is a lesion in the nerve root characterized by a burning pain and skin eruptions in dermatomal distribution. The inflammatory reaction precipitates stimulation of nerves producing a burning pain that precedes and often accompanies the skin eruptions.

General Concepts of pain management: Acute vs. chronic pain There are several key concepts for pain management. Pain is best treated early and a vigilant search for the cause is imperative. Pain scales should be utilized in order to gauge progression of pain (i.e. getting worse or better). Unrelieved pain is implicated with negative physiological and psychological conditions. For acute pain an opioid (morphine) is a suitable agent to control moderate to severe pain. Acute pain is usually a symptom of injury or illness and serves a biological purpose (i.e. to provoke treatment of the injury). Additionally, acute pain causes anxiety, has identifiable pathology (disease) and is present less than six months. In cases of chronic pain, the dysesthesias is the problem itself and serves no biological function. Chronic pain syndromes with dysesthesias are often implicated with depression due to chronicity (long-term illness). Chronic pain may or may not have identifiable pathology and is present for more than six months.

Management of Pain The first step to management of patients with neuropathic pain is to gain a good explanation of the cause and origin of the pain. Tricyclic antidepressants have an important role for the treatment of neuropathic pain (especially the “burning pain” associated with diabetes). These medications seem to be effective in several “pain” syndromes. Tricyclics tend to help with “burning” type pains, lacinating pains and cutaneous hyperalgesia. Tricyclics have an analgesic effect, thought to be mediated by alterations in brain chemistry (two specific neurotransmitters called serotonin and norepinephrine). Anticonvulsants (antiepileptic medications) can help reduce lacinating pain. Topical local aesthetic preparations (i.e. EMLA cream, eutectic mixture of local anesthetics) can penetrate skin and temporarily relieve neuropathic pain. The use of long term opioid treatment is unclear and should be reserved to selective cases. The use of capsaicin (the active substance extracted from hot pepper, can relieve pain (if placed on skin) in approximately 33% of patients with painful post-herpetic neuralgia and diabetic neuropathy.

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BOOKS

Canale, S. Terry. Campbell’s Operative Orthopedics, 10th ed. St. Louis: Mosby, Inc., 2003. DeLee, Jesse, G., and David Drez. Delee and Drez’s Orthopedic Sports Medicine, 2nd ed. Philadelphia: Saunders, 2003. Goetz, Christopher G., et al., eds. Textbook of Clinical Neurology, 1st ed. Philadelphia: W. B. Saunders Company, 1999. Goldman, Lee, et al. Cecil’s Textbook of Medicine, 21st ed. Philadelphia: W. B. Saunders Company, 2000. Marx, John A., et al., eds. Rosen’s Emergency Medicine: Concepts and Clinical Practice. 5th ed. St. Louis: Mosby, Inc., 2002. Noble, John, et al., eds. Textbook of Primary Care Medicine. 3rd ed. St. Louis: Mosby, Inc., 2001. PERIODICALS

Pascuzzi, Robert, M. “Peripheral neuropathies in clinical practice.” Medical Clinics of North America 87, no. 3 (May 2003). WEBSITES

National Institute of Neurological Disorders. . ORGANIZATIONS

NIH Neurological Institute. PO Box 5801, Bethesda, MD 20824. 301-496-5751 or 1-800-352-9424. .

Laith Farid Gulli, M.D. Nicole Mallory, M.S., PA-C Alfredo Mori, M.B., B.S.

❙ Dysgeusia Definition

Dysgeusia is a disorder of the sense of taste.

Description Any condition that affects the ability to taste is referred to as dysgeusia. While dysgeusia is often used to describe any change in the sense of taste, more specific terms include ageusia (complete loss of the sensation of taste); hypogeusia (decreased sense of taste); parageusia (bad taste in the mouth); and dysgeusia (distorted sense of taste, such as a metallic taste in the mouth). A wide variety of conditions can cause a deficit in the sense of taste, including any conditions that interfere with the functioning of the taste buds (the nerve cells on the tongue that process information about taste), conditions that interrupt the taste signal that is sent to the brain, or conditions that interfere

with the normal brain processing of those signals. Processes that affect the functioning of the lingual nerve or the glossopharyngeal nerve may impair the sense of taste. Furthermore, the sense of taste is frequently dulled or impaired due to dysfunction of the sense of smell.

Causes and symptoms There are a wide variety of conditions that can cause dysgeusia, including: • smoking • respiratory infections (colds, sinus infections, throat infection, or pharyngitis) • strep throat • inflammation of the tongue (glossitis) • gingivitis • influenza • dry mouth (due to medications or disorders such as Sjogren’s syndrome or salivary gland disorders or infections) • vitamin deficiencies (such as B-12 and zinc) • Cushing’s disorder • cancer • diabetes • hypothyroidism • liver or kidney failure • head injuries • brain tumors or other tumors that destroy or injure areas of the nose, mouth, throat, or brain responsible for taste • nasal polyps • Bell’s palsy • multiple sclerosis In addition, normal aging usually includes a decrement in the sense of taste as the numbers of taste buds decrease over time. A large number of medications can affect the sense of taste; antibiotics and cancer chemotherapeutic agents are common culprits. Examples of drugs that are known to cause dysgeusia include lithium, penicillamine, procarbazine, rifampin, vinblastine, vincristine, captopril, griseofulvin, and thyroid medications. Radiation therapy may cause dysgeusia. Symptoms of dysgeusia include decreased acuity of the sense of taste or the distorted perception of an odd taste. Complete loss of taste sensation is relatively rare.

Diagnosis Diagnosis can be made by having an individual taste and smell a variety of test substances. CT or MRI imaging may reveal the disorder underlying the development of dysgeusia.

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Resources

Dysgeusia Bitter Sour

Circumvallate papillae Filiform papillae Salt Sweet

Fungiform papillae

Trough Taste buds

Diagram of the tongue and taste buds. (Illustration by Electronic Illustrators Group.)

Treatment team Dysgeusia may be treated by a neurologist or by the physician who is treating the underlying condition responsible for the disorder (such as an otorhinolaryngologist for various ear, nose, or throat conditions, such as nasal polyps).

completely when the individual stops using the medication or discontinues smoking. However, dysgeusia due to more permanent damage to the neurological apparatus responsible for taste or smell (such as head injury, multiple sclerosis, radiation treatments, or diabetes) may never improve.

Special concerns Treatment Some types of dysgeusia resolve on their own, particularly dysgeusia that occurs due to an infection. When the infection clears, the dysgeusia usually abates and the sense of taste returns. When smokers stop smoking, their sense of taste may improve over time. Stopping some medications may also lead to an improved sense of taste. Individuals who suffer from dry mouth (xerostomia) may benefit from artificial saliva. Individuals with nasal polyps may note improved sense of taste after polyp removal.

Resources

Prognosis

BOOKS

Dysgeusia secondary to infection or reversible conditions like Bell’s palsy may improve partially or completely with resolution of the infection or condition; dysgeusia due to medication use or smoking may also improve partially or 310

Individuals with severely compromised taste or smell may inadvertently eat spoiled foods, leading to food-borne illness. Furthermore, without a good sense of smell or taste, there is an increased risk that an individual will not be able to protect him- or herself from exposure to other toxins, pollution, or smoke. Individuals with an impaired sense of taste may over-salt or over-sugar their food, in an attempt to compensate. They may not take in a reasonably balanced, nutritious diet with sufficient calories, because eating may become unenjoyable.

Pryse-Phillips, William, T. Jock Murray, and James Boyd. “Toxic Damage to the nervous system.” In Noble: Textbook of Primary Care Medicine, edited by John Noble, et al. St. Louis: W. B. Saunders Company, 2001.

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Bromley, Steven M. “Smell and Taste Disorders: A Primary Care Approach.” American Family Physician (January 2000). Ritchie, C. S. “Oral health, taste, and olfaction.” Clin Geriatr Med 18, no. 4 (November 2002): 709–717

Rosalyn Carson-DeWitt, MD

Key Terms Ataxia Failure of muscular coordination due to muscle disorder. Chronic Over a long period of time. Flexion (flex) To move a limb toward the body. Kinetic Word taken from the Greek (kinesis): motion.

❙ Dyskinesia Definition

Dyskinesias are a group of disorders characterized by involuntary movements of muscles.

Description Dyskinesias are excessive abnormal movements that are involuntary. There are several different types of dyskinesias, and each has different clinical symptoms, causes, and treatments. Adults and children with certain chronic brain disorders often exhibit symptoms of dyskinesia. Movement can occur in the head, arms, legs, hand, feet, lips, or tongue. The dyskinesias can be categorized as chorea, dystonia, myoclonus, tremor, and paroxysmal tardive (late-onset type). Other forms of dyskinesia include athetosis, ballism, akathisia, tics, stereotypy, and restless legs. Dyskinesias can also be called hyperkinesia syndromes.

Chorea Choreas are abnormal movements that are irregular, involuntary, nonrhymical, abrupt, rapid, and nonsustained jerking, which continuously flow from one body part to another. Movements are isolated, brief, and infrequent. Chorea can cause inability to maintain a sustained contraction, which causes affected persons to drop objects. Persons with chorea have an irregular dance-like gait. The cause of chorea is not completely understood.

Dystonia Dystonia that occurs at rest may persist as the kinetic (clonic) form. Dystonias can be either focal or generalized. Focal dystonias are involuntary movements in a single body part, which commonly includes blepharospasm (upper facial), spasmodic torticollis (cervical), and writer’s cramp. Dystonia affecting two or more body regions is called segmental dystonia. Generalized dystonia typically affects the trunk, one or both legs, and another body part. Other types of dystonias include Merge’s syndrome (spasms of the jaw muscles when opening and closing of

Neuroleptic Negative effects of thinking and behavior, creating a state of apathy and lack of initiative. Retrocollis Muscular spasms that affect the neck muscles located in the back. Torticollis Contracted neck muscle, causing twisting of the neck in an abnormal position. Unilateral On one side.

the mouth). Spasmodic dystonias can cause speech impairment due to spasms of laryngeal (throat) muscles. The intensity of muscular movements in patients with dystonia can fluctuate, and symptoms worsen during fatigue, stress, activity, and change in posture. In some cases, the bizarre symptoms of dystonia can be mistaken for psychological illness. Dystonias can be inherited or acquired due to another primary cause. Inherited diseases that exhibit dystonia are rare and include dopa-responsive dystonia, idiopathic tension dystonia, and x-linked dystoniaParkinsonism (found among Ashkenazi Jews).

Myoclonus Myoclonus refers to muscular contractions (positive myoclonus) that are brief, sudden, and severe, and shocklike movements or inhibitions (negative myoclonus). Myoclonus could be generalized or isolated. The movements consist of rhythmical irregular jerks or oscillatory jerks that occur abruptly and then fade. The abnormal jerks are associated with environmental stimuli such as light, sound, movement, and visual threat. The condition can be misdiagnosed for epilepsy. Myoclonus usually occurs at rest, but can also appear when the affected body part is subjected to voluntary activity, which is referred to as action myoclonus. Action myoclonus is more disabling than rest myoclonus.

Tremor Tremors are rhythmic oscillatory movements that are regular, but may vary in rate, location, amplitude, and constancy, and depend on type and severity of the tremor.

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PERIODICALS

Dyskinesia

Tremors can occur with action, at rest, and with holding a position or posture. The tremor can be so rapid it is often described as a “flicker of light.” Subtypes of tremors include tremors at rest, essential tremor, which is a postural tremor at either rest or activity and may be inherited, or tremor with movement (intention “kinetic” tremor). Resting tremors are usually slow, occur during an activity, and disappear when action is initiated (e.g., Parkinson’s disease). Essential tremor is usually benign, but can cause disability due to impairment of handwriting and limitations of activities related to daily living. Essential tremor may be inherited.

Paroxysmal dyskinesias Paroxysmal dyskinesia is a group of disorders that includes paroxysmal kinesigenic dyskinesia, episodic ataxia, paroxysmal hypnogenic dyskinesia, paroxysmal exertion-induced dyskinesia, and paroxysmal non-kinesigenic dyskinesia. The paroxysmal dyskinesias are a hyperkinetic disorder characterized by intermittent involuntary movements consisting of symptoms from other movement disorders such as chorea, athetosis, dystonia, and ballismus. Episodes of paroxysmal dyskinesias can last from a few seconds to several days. Episodic ataxias are characterized by intermittent episodes of ataxia that can last seconds to hours. Paroxysmal dyskinesias may be triggered by prolonged exertion, sleep, stress, alcohol, coffee, tea, fatigue, sudden voluntary movement, heat, or cold.

Athetosis Athetosis is a disorder characterized by movements that are continuous, slow, and writhing. The movements are commonly appendicular and frequently involve muscles in the face, neck, and tongue. The condition may occur at rest or when executing voluntary movement. The speed of movements in affected persons can sometimes increase and symptoms are similar to those of chorea (called choreoathetosis). Athetosis movements can blend with those of dystonia, if the muscular contractions are sustained and cause abnormal posturing.

Ballism Ballismus are large choreic movements that are fast and usually affect the limbs. Affected individuals exhibit flinging and flailing movements. Commonly, ballismus affects one side of the body (unilateral), producing a condition called hemiballismus.

Akathisia Akathisia refers to complex movements such as tics, compulsions, and mannerisms that are stereotypic and usually relieved when executing a motor act. Typically, 312

when sitting, the akathitic persons may exhibit movements that include symptoms such as crossing and uncrossing the legs, squirming, pacing, stroking the scalp, or rocking the body. Patients may have burning sensations on the specific affected body part, and they may vocalize a continual moaning and groaning.

Tics Tics can be divided into two disorders: motor tics (abnormal movements) and/or vocal tics (abnormal sounds). Children can present with a chronic disorder of both motor and vocal tics (Gilles de la Tourette syndrome). Movements of simple tics may be very similar to a choreic or myoclonic jerk (abrupt, single, sudden, isolated). Complex tics are movements that are distinctly coordinated patterns of sequential movements, but they may not be identical from occurrence to occurrence and they can occur in different body areas. Tics are rapid movements and, if contractions are sustained in affected body parts, they resemble dystonic movements. One of the major clinical signs that help distinguish tics from other dyskinesias is the presence of involuntary ocular (eye) movement in persons affected with tics. The ocular manifestations of tics can include a brief jerk of the eyes or a sustained eye deviation. Two other dyskinesias, myoclonus and dystonia, can present with involuntary ocular manifestations. With vocal tics, affected persons can exhibit grunts, throat-clearing sounds, or even the utterance of obscenities (coprolalia). Phonic tics (involving nasal and vocal muscles) can be divided into simple phonic tics such as throatclearing or sniffing or complex phonic tics that include bark-like noises and verbalizations.

Stereotypies Sterotypies are movements that are frequent and may last for minutes. These movements are repetitive and identical (continuous stereotypy.) The bizarre movements associated with mental retardation, autism, and schizophrenia are stereotypies. Continuous stereotypy is characteristic of another type of dyskinesia called tardive dyskinesia, which results from treatment with neuroleptic and antipsychotic medications.

Tardive dyskinesia Tardive (late-onset) dyskinesia refers to a group of movement disorders that are characterized by hyperkinetic involuntary movements, consisting of mixed manifestations of orofacial dyskinesia, chorea, tics, and/or athetosis. Abnormal movement can affect muscles in the lips, face, trunk, tongue, and extremities, which can interfere with eating and dexterity. The most characteristic symptom of

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Tardive dyskinesias are commonly seen in patients taking certain medications such as neuroleptics and antipsychotic medication that are prescribed for schizophrenia, schizoaffective disorder, or bipolar disorder. Other types of tardive dyskinesias include tardive akathisia, tardive dystonia, tardive myoclonus, tardive Tourettism, tardive tremor, and blepharospasm. Approximately 50% of patients taking dopamine receptor blocker medication will develop a form of tardive dyskinesia. Tardive akathisia refers tapping, squirming, and marching movements that are repetitive. Movements associated with tardive dystonia can include a fixed posturing of face and neck, trunk, and extremities. Persons affected with tardive myoclonus, which is a rare disorder, exhibit brief jerky movements of muscles in the face, neck, trunk, arms, and legs. Symptoms of tardive Tourettism usually begins in persons older than 21 years of age and include frequent, multiple tics that are both vocal and motor. This disorder should not be confused with Tourette syndrome, which commonly presents by seven years of age. Tardive tremors often present as involuntary rhythmical, wave-like, and persistent movements of the head, neck, limbs, or voice. Tardive tremors are present both at rest and during voluntary movement.

Early myoclonic encephalopathy Early myoclonic encephalopathy is a rare disorder, in which the incidence is approximately one in 40,000 children. It is characterized by brief and abrupt myoclonic jerks (common occurrence in 90% of patients) and seizures. The onset of symptoms usually occurs within the first three years of life. Treatment and management depends on the underlying cause of seizures. Typically, patients receive antiepileptic medications, and improvement of symptoms is usually associated with a good prognosis. If symptoms do not improve with antiepileptic medication(s), the prognosis is not favorable. Resources BOOKS

Goetz, Christopher G., et al. (eds). Textbook of Clinical Neurology. 1st ed. Philadelphia: W.B. Saunders Company, 1999. Goldman, Lee, et al. Cecil’s Textbook of Medicine. 21st ed. Philadelphia: W.B. Saunders Company, 2000. Noble, John, et al, (eds). Textbook of Primary Care Medicine. 3rd ed. St. Louis: Mosby, Inc., 2001.

PERIODICALS

Brasic, James R. “Tardive Dyskinesia.” eMedicine Series (December 2003). Jankovic, J., and M. Demirkiran. “Paroxysmal Dyskinesias: An Update.” Annals Medical Science 10 (2001). Jenner, Peter. “Avoidance of Dyskinesia: Preclinical Evidence for Continuous Dopaminergic Stimulation.” Neurology 62:1 (January 2004). WEBSITES

Gardos, G., and J. O. Cole. The Treatment of Tardive Dyskinesias. (May 20, 2004). . ORGANIZATIONS

American College of Neuropsychopharmacology. 320 Centre Building 2014 Broadway, Nashville, TN 37203. (615) 322-2075; Fax: (615) 343-0662. [email protected].

Laith Farid Gulli, MD Nicole Mallory, MS, PA-C

❙ Dyslexia Definition

Dyslexia is an unexpected impairment in reading and spelling despite a normal intellect.

Description Dyslexia was first described by Hinshelwood in 1896. Orton originally hypothesized that dyslexia results from a dysfunction in visual memory and visual perception due to a delayment in maturation. Most dyslexics also display poor writing ability. Dyslexia is a classical primary reading disorder and should be differentiated from secondary disorders such as mental retardation, educational or environmental deprivation, or physical/organic diseases. The disorder results as a combination of genetic and environmental causes, which can induce variations in the behavioral, cognitive, and physiological measures related to reading disability. Dyslexia was previously called congenital word blindness. Dyslexia is a reading disorder, not caused by lowered motivation, inadequate learning opportunity or any overt neurological disability. Reading is a complex process which involves multiple systems to process the information cognitively and physiologically. In simple terms reading typically begins with a visual sensation stimuli and processing the text via the visual pathway in the brain (from the retina in the eye, the impulse goes in the brain to the lateral geniculate nuclei and primary visual cortex, the occipital lobe, located in the back of the head, which functions to process and integrate incoming visual

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tardive dyskinesia is orofacial dyskinesia, which usually starts with slow, mild tongue movements followed by exaggerated movements of lips and tongue. Affected individuals can have symptoms that may progress to chewing movements, blinking, bulging cheeks, grimacing, arching eyebrows, and blepharospasms.

Dyslexia

information). Input information from vision is probably integrated with other neuronal systems that include language-specific rules, learned information and symbolic images into components of language thinking related to reading. Reading-related thinking is correlated with high activity in the left-hemisphere cortical regions, and language processing centers in the brain. Additionally, learning to read is also related to the learning process, which is mediated by the cerebellum and on relay feedback mechanisms between related areas of the brain. Deficits in reading may stem from disruptions of simple sensory impairments to more complex problems involving thinking related to language. There are several subtypes of dyslexias and they can be categorized as either central or peripheral dyslexias (of which there are two, attentional dyslexia and neglect dyslexia), which result from impairment to brain processes that are capable of converting letters on the page into visual word forms. There are two types of peripheral dyslexias called attentional dyslexia, and neglect dyslexia. The attentional dyslexia subtype is a rare disorder of attention control, typically correlated with damage to the left parietal lobe (located on the sides of the head). The attentional dyslexia causes an impairment of reading words in sentences, since the defect causes many words to be visible at the same time. Neglect dyslexia is usually due to brain damage, and causes an impairment of reading because the affected person misidentifies letters in certain spatial regions of either a word or a group of words. The defect for neglect dyslexia subtype is associated with the right parietal lobe. Neglect dyslexia can be further divided into left neglect dyslexia and right neglect dyslexia. In the left neglect dyslexia subtype, the affected person experiences difficulty reading initial letters of the word, which may cause a letter(s) to be substituted, omitted or added. The right neglect dyslexia subtype causes a patient to have letter errors at the end of the word. Letter-by-letter reading (LBL, pure alexia, or pure word blindness) is another form of peripheral dyslexia causing patients to have very slow reading performance with large effects on word length and response time. There is damage to the prestriate cortex of the occipital cortex and most patients also have a dense right visual field deficit. The damage impairs the word-form system in an abnormal way so that written words seem as random letter strings. Central dyslexias are typically caused by disruption to neuronal processes correlated with sound analysis and meaning of written words. There are two major subtypes of central dyslexias which either impair semantic reading or nonsemantic reading. Semantic reading dyslexia is also referred to as deep and phonologic dyslexia. Semantic reading is due to extensive damage to the left hemisphere which results in a deficit whereby patients can only assemble the pronunciation of a word by first assessing its

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Key Terms Attention deficit/hyperactivity disorder (ADHD) A disorder associated with behavioral control, due to difficulty processing neural stimuli. Dizygotic twins Twins that share the same environment during development in the uterus but are not identical. Lateral geniculate nuclei A structure that receives and processes impulses from the optic nerve, and sends these impulses further into the brain for more processing of information. Monozygotic twins Twins that are genetically identical and are always of the same gender. Occipital lobe The back part of the brain that functions as a visual interpretation center. Parietal lobe Part of the cerebral hemisphere, located on both sides of the brain. Phoneme The smallest meaningful segment of language (e.g., the word “cat” has 3 phonemes, “kuh,” “aah,” and “tuh”). Retina Area of the eye that helps process visual information to send impulses to the brain. Temporal lobe A lobe of the brain that contains auditory and receptive (stimuli) areas. Visual field A field of vision that is visible without eye movement.

meaning. Affected individuals also make visual errors when reading. Nonsemantic reading, due to damage of the left temporal lobe causes patients to have difficulty reading exception words (i.e. shove), but can read correctly words that are common and similar (i.e. love).

Demographics It is thought that dyslexia is the most common neurobehavioral disorder affecting children. The prevalence (existing cases) ranges from 5-10% of school-aged children (school and clinic identified) in the United States. However, these rates may be significantly more (up to 17.5%) in unselected populations. Research indicates that dyslexia is a chronic and persistent disorder. Evidence concerning gender predilection remains controversial. Dyslexia may also co-occur with another disorder called attention deficit/hyperactivity disorder (ADHD, 40% comorbidity). Dyslexia affects approximately 80% of children identified as manifesting a learning disorder.

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Persons affected with dyslexia have dysfunction developing an awareness of spoken and written words and segmenting smaller units of sound that are essential in an alphabetic language like English. Patients lose the ability to link and map printed symbols (letters) to sound. Dyslexia runs in families. Studies demonstrate concordance rates of 68% for monozygotic twins and 37% for dizygote twins (Colorado Twin Study of Reading Disability). However, the genetic transmission is not simple and does not follow classical knowledge of trait heritability. Findings suggest that several genetic factors determine reading ability and the interactions of some or all factors determine the ultimate ability to read. Evidence from neurobiological research utilizing high resolution imaging techniques, and brain measurement studies indicate differences in left temporo-parieto-occipital brain regions in dyslexic patients when compared to nonimpaired readers. Furthermore, evidence using functional brain imaging techniques in adult and children with dyslexia demonstrates a failure of normal left hemisphere posterior brain systems during reading with increased brain activation in frontal regions. This data indicates that impairment of posterior reading systems results in a disruption of the smoothly functioning and integrated reading system seen in nonimpaired persons. The impairment of posterior reading systems causes dyslexic persons to shift to ancillary neuronal systems to compensate for the deficit. It is the impairment in the posterior reading systems that prevents the development of skilled reading. Postmortem studies (confirmed in live subjects using MRI imaging) indicate a lack of symmetry in language-associated regions in the brain. The abnormal symmetry is associated with the common linguistic deficits that are characteristic of dyslexia. The specific signs of dyslexia in both adults and school-aged children are similar. Patients exhibit inaccurate and labored decoding, word recognition, and text reading. They also exhibit difficulties in spelling and remain slow readers. Typical early symptoms can include difficulty playing rhyming games and problems with learning numbers and letters. Children often avoid reading independently and are unusually happy at the opportunity for parents to read to them.

Diagnosis All cases and ages are diagnosed clinically by a combination of careful medical history, observation and psychological testing. There is no one test that is sufficient to render a definitive diagnosis. Rather, the diagnosis is made based on the results of all the clinical data attained.

Dyslexia can be distinguished from other learning disorders by identifying the phonologic deficit. Family history and collateral data obtained from school and test results are essential. Tests to determine attention, memory, intelligence and math and language skills may be administered to establish the diagnosis.

Treatment team The treatment team can consist of a neurologist, a pediatrician, and special education instructors. A clinical psychologist can perform psychological assessments (psychometric testing) to help establish the diagnosis. School and/or college counselors also comprise part of an effective and integrated treatment team.

Treatment The management for dyslexic patients is lifelong. Early identification and intervention (remediation) of reading deficits involves specialist education. Intervention programs must systematically and explicitly teach phonics ensuring a clear understanding of how letters are linked to sounds (phonemes) and spelling. Typically individualized teaching is recommended to provide a balanced remedial program providing systematic instruction on phonemic awareness, phonics, vocabulary fluency and comprehension strategies. A well-integrated treatment program also includes opportunities for writing, reading, and discussing literature. A well-executed treatment program considers each component of the reading process to improve phonemic awareness and the ability to manipulate speech sounds. Treatment for older persons (high school, college, and graduate school) is accommodation rather than remediation. College students require extra time with examination and reading/writing assignments. Other accommodations include recorded books, tape recorders in the classroom, tutorial services, alternatives to multiple choice questions and computer availability with spelling checkers.

Recovery and rehabilitation Rehabilitation for dyslexics is a lifelong process. Early intervention in younger patients consists of a highly structured, integrated, systematic and explicit treatment program. A balanced treatment program should include the meaning and phonetic approaches to reading to ultimately improve language development (since dyslexia is a language-based disorder.) The program should allow for personalized instruction. Older persons require accommodation in college and at work versus remediation.

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Causes and symptoms

Dyspraxia

Special concerns Early recognition, intervention, and family members are important. Remediation programs must be delivered by highly-trained specialists, and treatment should be individualized. Resources BOOKS

Behrman, Richard, E., et al., eds. Nelson Textbook of Pediatrics. 17th ed. Philadelphia: Saunders, 2004. PERIODICALS

Brow, W. E., A. L. Reiss, and S. Eliez. “Preliminary evidence of widespread morphological variations of the brain in dyslexia.” Neurology 56, no. 6 (March 2001). Bub, Danial. “Alexia and related reading disorders.” Neurological clinics 21, no. 2 (May 2003). Francks, C., and L. Macphie. “The genetic basis of dyslexia.” The Lancet Neurology 1, no. 8 (December 2002). Olitsky, Scott E. “Reading disorders in children.” Pediatric Clinics of North America 50, no. 1 (February 2003). Wood, F., and E. L. Grigorenko. “Emerging Issues in the Genetics of Dyslexia: A Methodological Preview.” Journal of Learning Disabilities 34, no. 6 (NovemberDecember 2001). WEBSITES

Dyslexia. . The International Dyslexia Association. . ORGANIZATIONS A child with dyslexia, writing words incorrectly. (Photograph by Robert Huffman. Field Mark Publications. Reproduced by permission.)

Clinical trials There are two current clinical research trials entitled: Comprehensive Program to Improve Reading and Writing Skills in At-Risk and Dyslexic Children; and Using MRI to Evaluate Instructional Programs for Children with Developmental Dyslexia. Information can be obtained from http://www.ClinicalTrails.com.

The National Center for Learning Disabilities. 381 Park Avenue South, Suite 1401, New York, NY 10016. (212) 545-7510 or 888-575-7373; Fax: (212) 545-9665. . The International Dyslexia Association. 8600 LaSalle Road, Baltimore, MD 21286-2044. 410-296-0232 or 800ABCD123; Fax: 410-321-5069. .

Laith Farid Gulli, MD Nicole Mallory, MS, PA-C Robert Ramirez, DO

Dysphagia see Swallowing disorders

Prognosis Dyslexia is a lifelong disorder, but improvement is possible. Multiple learning disabilities can be expected, since the brain connections for reading, spelling, listening, speaking, and writing are part of the linguistic system. The prognosis can ultimately depend on associated comorbidities (other disorders associated with the primary disorder), early detection and intervention, and an intensive and comprehensive treatment plan.

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❙ Dyspraxia Definition

Dyspraxia is a neurological disorder of motor coordination usually apparent in childhood that manifests as difficulty in thinking out, planning out, and executing planned movements or tasks. The term dyspraxia derives

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Description The earliest description of a syndrome of clumsiness, termed “congenital maladroitness,” dates back to the turn of the twentieth century. Since that time, numerous names have been given to this syndrome of impaired coordination, including dyspraxia, developmental dyspraxia, developmental coordination disorder, clumsy child syndrome, and sensory integration disorder. Some sources ascribe different meanings to these terms, while others use them interchangeably. Researchers commonly use the term developmental coordination disorder (DCD); DCD is classified by the Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition, Text Revision (DSMIV-TR) as a motor skills disorder. Dyspraxia is a variable condition; it manifests in different ways at different ages. It may impair physical, intellectual, emotional, social, language, and/or sensory development. Dyspraxia is often subdivided into two types: developmental dyspraxia, also known as developmental coordination disorder, and verbal dyspraxia, also known as developmental apraxia of speech. Symptoms of the dyspraxia typically appear in childhood, anywhere from infancy to adolescence, and can persist into adult years. Other disorders such as dyslexia, learning disabilities, and attention deficit disorder often co-occur in children with dyspraxia.

Demographics Estimates of the prevalence of developmental coordination disorder are approximately 6% in children aged 5–11. Some reports indicate a higher prevalence in the 10–20% range. Males are four times more likely than females to have dyspraxia. In some cases, the disorder may be familial.

Causes and symptoms Developmental dyspraxia is apparent from birth or early in life. As of 2004, the underlying cause or causes for dyspraxia remain largely unknown. It is thought that any number of factors such as illness or trauma may adversely affect normal brain development, resulting in dyspraxia. Genes may also play a role in the development of dyspraxia. It is known that dyspraxia can be acquired (acquired dyspraxia) due to brain damage suffered as a result of stroke, an accident, or other trauma. Symptoms of dyspraxia vary and may include some or all of the following problems: • poor balance and coordination

• vision problems

Dyspraxia

from the Greek word praxis, meaning “movement process.”

• perceptual problems • poor spatial awareness • poor posture • poor short-term memory • difficulty planning motor tasks • difficulty with reading, writing, and speech • emotional and behavioral problems • poor social skills The symptoms of dyspraxia depend somewhat on the age of the child. Young children will have delayed motor milestones such as crawling, walking, and jumping. Older children may present with academic problems such as difficulty with reading and writing or with playing ball games. Developmental verbal dyspraxia (DVD), a type of dyspraxia, can manifest as early as infancy with feeding problems. Children with DVD may display delays in expressive language, difficulty in producing speech, reduced intelligibility of speech, and inconsistent production of familiar words.

Diagnosis The diagnosis of dyspraxia is based on observation of a patient’s symptoms and on results of standardized tests. Findings from a neurological or neurodevelopmental evaluation may also be used to confirm a suspected diagnosis. The process of making a diagnosis of dyspraxia can be complex for a number of reasons. Dyspraxia may affect many different body functions, it can occur as a part of another syndrome, and symptoms of dyspraxia overlap with similar disorders such as dyslexia. Diagnostic criteria Various health professionals and organizations define the term dyspraxia differently. The Dyspraxia Foundation (England) describes it as “an impairment or immaturity of the organization of movement,” and further adds that it may be associated with problems in language, perception, and thought. Other advocacy groups such as the Dyspraxia Association of Ireland and the Dyspraxia Foundation of New Zealand, Inc. offer slightly different definitions. The American Psychiatric Association lists four criteria in the DSM-IV-TR for the diagnosis of developmental coordination disorder: • marked impairment in the development of motor coordination • the impaired coordination significantly interferes with academic achievement or activities of daily living

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• the coordination difficulties are not due to a general medical problem such as cerebral palsy or muscular dystrophy and do not meet the criteria for pervasive developmental disorder • if mental retardation (MR) is present, the motor coordination problems exceed those typically associated with the MR

Treatment team Treatment for individuals with dyspraxia is highly individualized because the manifestations vary from patient to patient. The treatment team for a child with dyspraxia may include a pediatric neurologist, a physical therapist, an occupational therapist, and a speech therapist, in addition to a family doctor or pediatrician. In some cases, the treatment team may also include a psychologist, a developmental optometrist, and specialists in early intervention or special education.

Treatment Currently there is no cure for dyspraxia. Treatment mainly consists of rehabilitation through physical, occupational, and speech therapies. Other interventions such as special education, psychological therapy, or orthoptic exercises may be recommended on a case-by-case basis. The purpose of treatment for dyspraxia is to help the child to think out, plan out, and execute the actions necessary to try out new tasks or familiar tasks in novel ways.

Recovery and rehabilitation There are specific therapies for dyspraxia. In physical therapy, a physical therapist may evaluate some or all of the following skill areas in order to formulate a plan of treatment with the patient’s physician: • muscle tone • control of shoulders and pelvis • active trunk extension and flexion (posture)

• motor planning (ability to plan movements needed to move from one position to another) • self organization (dressing, eating, etc.) • eye tracking Physical therapy generally consists of activities and exercises designed to improve the specific skill weakness. For example, activities such as climbing, going through tunnels, and moving in and out of cones may assist a child who has poor spatial awareness. The physical therapist may also recommend that the child practice the treatment activities or exercises at home. In occupational therapy, an occupational therapist may use standardized tests to evaluate the child’s sensory integration skills. A therapeutic technique known as sensory integration may be recommended. Sensory integration techniques help a child to sort, store, and integrate information obtained by the senses so that it may be used for learning. In speech therapy, a speech therapist may assist the child with areas such as muscle control, planning language, and forming concepts and strategies in order to communicate. The therapist may use language tests to assess language comprehension and production in order to develop a plan of treatment

Clinical trials As of 2004, there was one clinical trial recruiting patients with a form of dyspraxia known as verbal dyspraxia. The aim of the study, entitled “Central Mechanisms in Speech Motor Control Studied with H2150 PET,” is to use radioactive water (H2150) and positron emission tomography (PET) scan to measure blood flow to different areas of the brain in order to better understand the mechanisms involved in speech motor control. Information on this trial can be found at (see study number 92-DC-0178) or by contacting the National Institute on Deafness and Other Communication Disorders (NIDCD) patient recruitment and public liaison office at (800) 411-1010.

• hand-eye coordination (throwing a ball)

Prognosis

• foot-eye coordination (kicking a ball) • midline crossing (writing) • directional awareness (ability to move in different directions) • spatial awareness (judge distances and direction) • integration (moving both sides of the body simultaneously) • knowledge of two sides/dominance of one side (knowing right from left) • short-term memory 318

The prognosis for dyspraxia varies. Some children “outgrow” their condition, whereas others continue to have difficulties into adulthood. Though early diagnosis and prompt treatment may improve the outcome for a given patient, the precise factors that influence prognosis are not well understood. For example, it remains unclear how factors such as a child’s specific deficits and the underlying cause for the disorder influence rehabilitation potential. Also, the prognosis for dyspraxia is situational; it depends on the age of the patient and the demands of a given setting or environment.

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A child with a diagnosis of dyspraxia or developmental coordination disorder may be eligible to have an individual education plan (IEP). An IEP provides a framework from which administrators, teachers, and parents can meet the educational needs of a child with dyspraxia. Depending upon severity of symptoms and the presence of other problems such as learning difficulties, children may be best served by special education classes or by a private educational setting.

+64 3 359 7074. [email protected].

Dawn J. Cardeiro, MS, CGC

Dyssynergia cerebellaris myoclonica see Ramsey-Hunt syndrome type II

❙ Dystonia

Resources BOOKS

American Psychiatric Association. Diagnostic and Statistical Manual of Mental Disorders, 4th edition, text revision. Washington, DC: American Psychiatric Association, 2000. Macintyre, C. Dyspraxia 5–11: A Practical Guide. London: David Fulton Publishers, 2001. Portwood, M. Understanding Developmental Dyspraxia: A Textbook for Students and Professionals. London: David Fulton Publishers, 2000. PERIODICALS

Cousins, M., and M. M. Smyth. “Developmental Coordination Impairments in Adulthood.” Hum Mov Sci 22 (November 2003): 433–59. Flory, S. “Identifying, Assessing and Helping Dyspraxic Children.” Dyslexia 6 (July–September 2000): 205–8. McCormick, M. “Dyslexia and Developmental Verbal Dyspraxia.” Dyslexia 6 (July–September 2000): 210–4. Payton, P., and M. Winfield. “Interventions for Pupils with Dyspraxic Difficulties.” Dyslexia 6 (July–September 2000): 208–10. WEBSITES

Apraxia Kids Home Page. (May 30, 2004). . The Dyspraxia Support Group of New Zealand Home Page. (May 30, 2004). . Developmental Dyspraxia Information Page. The National Institute of Neurological Disorders and Stroke (NINDS). (May 30, 2004). . ORGANIZATIONS

American Speech Language Hearing Association (ASHA). 10801 Rockville Pike, Rockville, MD 20852-3279. (301) 897-5700 or (800) 638-8255; Fax: (301) 571-0457. [email protected]. . The Dyspraxia Foundation. 8 West Alley, Hitchin, Hertfordshire SG5 1EG, United Kingdom. +44 (0) 14 6245 5016 or +44 (0) 14 6245 4986; Fax: +44 (0) 14 6245 5052. [email protected]. . The Dyspraxia Support Group of New Zealand, Inc. The Dyspraxia Centre, P.O. Box 20292, Bishopdale, Christchurch, New Zealand. +64 3 359 7072; Fax:

Definition

Dystonia is a disabling movement disorder characterized by sustained contraction of muscles leading to twisting distorted postures. Dystonia may affect various parts of the body and has multiple causes, making classification and diagnosis challenging. The etiology behind the various forms of dystonia is unknown, although abnormal functioning of the cerebral cortex and basal ganglia and other pathways involved in movement are presumed. Clinical and basic science research on humans and primates, and identification of multiple genes causing dystonia have improved the understanding and treatment of this debilitating disorder.

Description Dystonia as a term was first coined by Oppenheim in 1911 in reference to a childhood-onset syndrome he termed dystonia musculorum deformans. This entity, known as idiopathic torsion dystonia today, was noted to run in families, and although presumably inherited, was only recently proven to be of genetic cause. There is a wide range of variability in the manifestation of clinical symptoms of dystonia. Due to its various causes, dystonia is seen as a syndrome rather than a disease. Dystonia can be classified by age of onset, cause, or by distribution of the body parts affected. Dystonia localized to a single body part such as the hand or neck is referred to as focal. Among body parts affected in focal dystonia, the eyelids, mouth, muscles controlling the voice, neck, hand, or arm may be affected. Dystonia localized to two contiguous body parts is referred to as segmental. Dystonia affecting body parts that are not next to each other is referred to as multifocal. Dystonia affecting one segment and another body part is classified as generalized. It may also affect only one half of the body and be called hemidystonia. Dystonia with a known environmental cause is referred to as secondary. The cause of primary or idiopathic dystonias is unknown or genetic. The course and severity of dystonic symptoms may change over the duration of the illness. Symptoms may

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Special concerns

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initially involve one body part and then spread to other body parts. The likelihood of spread often depends on the age and site of onset of symptoms. Early onset dystonia may start in a limb but tends to become generalized. Adult onset dystonia may start in the neck or face muscles and tends not to spread. Dystonia may first occur only with voluntary movements, but in time, occur at rest as well.

Demographics Dystonia follows Parkinson’s disease and essential tremor as the most frequent movement disorder. Prevalence is estimated as 3.4 per 100,000 for generalized forms and 29.5 per 100,000 for focal dystonia. Early onset dystonia may be more frequent in patients of Jewish ancestry, especially from Eastern Europe or Ashkenazi background.

Causes and symptoms Causes The exact cause of dystonia is unknown. Ongoing research on dystonia is directed at examining the abnormal brain activity in different parts of the brain such as the basal ganglia and cerebral cortex. The basal ganglia are a collection of nerve cells that are part of the brain pathways important for regulating aspects of normal movement. Abnormalities in the processing of information in these pathways are thought to underlie the various movement disorders such as Parkinson’s disease, Huntington’s disease, tremor, and dystonia. There is evidence for abnormalities in the spinal cord and peripheral nerves as well, suggesting that dystonia may involve abnormalities at multiple levels of the nervous system. Patients with dystonia may have abnormal touch perception and sensation, and theories propose that there may be defects in the preparation of movement as well as the translation of sensation to movement. Dystonia can be classified by cause into primary and secondary forms. Primary or idiopathic dystonia is presumed to be of genetic or unknown cause, whereas secondary dystonias are due to an attributable cause. Primary dystonia Primary or idiopathic dystonias have no identifiable etiology and are presumed to be genetic in cause. There are currently at least 13 different genetic dystonia syndromes, although only a few genes have actually been isolated. The only identified gene for primary dystonia is DYT1 on chromosome 9. DYT1 dystonia tends to occur in childhood and starts in a limb only to generalize. The appearance of the dystonia may differ in individuals with the

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same genetic abnormality, suggesting that there are environmental factors involved as well. Primary genetic dystonias may appear in multiple family members, but most are due to new mutations in genes and referred to as sporadic. Primary dystonias tend to develop gradually over the course of months to years. Secondary dystonia Secondary dystonia can be caused by a structural abnormality of the brain such as a stroke or infection, drugs or various toxins or metabolic abnormalities. These tend to occur over the course of days to weeks due to the nature of an inciting insult. Dystonia may occur after birth trauma and may be delayed in onset for up to a decade or later. Some may occur as part of a larger disease process affecting other parts of the body such as Wilson’s disease, a defect of metabolism of copper that causes abnormal liver function and movement problems such as dystonia or tremor. Usually an abnormality will be found on brain imaging studies such as MRI or CT scan. Patients taking medications for psychiatric diseases such as schizophrenia or psychosis may develop dystonia as a drug reaction. Dystonia may be feigned as part of a psychiatric disorder and is then known as psychogenic. Other dystonias Dystonia may also be associated with other neurologic disorders. These are classified as dystonia-plus syndromes. Dystonia may be associated with Parkinson’s disease or myoclonus, another movement disorder which consists of muscle jerking. Dystonia may be part of a larger syndrome of neurodegenerative disorders, a group of diseases which are caused by degeneration of nerve cells in certain portions of the brain. Such disorders include Huntington’s disease and Parkinson’s disease. Symptoms The symptoms of dystonia depend on the body part affected. Dystonia localized to the face may involve repetitive blinking, tongue protrusion, or jaw clenching. Blinking can become so severe that the patient can not see due to inability to open the eyes. Dystonia affecting the neck may lead to sustained flexion, extension, or twisting postures of the neck known as torticollis. Some dystonias are task-specific and only arise during the performance of certain tasks such as writing, typing, or playing instruments. The progression of these symptoms can lead to severe disability and inability to perform daily work. Generalized dystonia, the most severe form, can present as twisting movements of the head, trunk, and arms, completely disabling the affected individual. Dystonia can often be associated with a tremor in the affected body part.

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Diagnosis The diagnosis of dystonia is clinical and is usually made by a neurologist who may have expertise with movement disorders. Investigation of dystonia will usually involve a physical examination and medical history taken by the neurologist to look for secondary causes such as drug exposure or stroke or other family members affected, suggesting a genetic cause. An MRI of the brain may be performed to look for a structural abnormality causing the symptoms. Laboratory testing may reveal abnormalities of copper metabolism associated with Wilson’s disease. Genetic testing for the DYT1 gene is not performed unless the dystonia is early in onset or there is a family history of similar symptoms.

Botox Chemical denervation using botulinum toxin has been used for many movement disorders including dystonia. Botulinum toxin blocks the transmission of nerve impulses to the muscle and paralyzes the overactive muscles involved. Focal forms of dystonia are more amenable to treatment due to the ease of localizing injectable muscles and less extensive involvement. Botox may be used in generalized dystonia to facilitate improvement in select muscles needed for daily function such as the arms and legs. Surgical treatment Selective destruction or high frequency stimulation of nerve centers involved in causing dystonia has been useful in treating selected patients with disabling symptoms. Patients with generalized dystonia or hemidystonia may benefit due to the widespread nature of symptoms, limiting the efficacy of medications and botox injections. Surgical lesioning of nerve cells in the globus pallidus or stimulation of cells in the globus pallidus or subthalamic nucleus have been shown to be effective in treating the symptoms of dystonia. The long-term benefit of surgical therapies on symptoms of dystonia has yet to be validated.

Treatment team Treatment for dystonia involves the interaction between a neurologist, psychiatrists, and physical and occupational therapists. Treatment may involve a neurosurgeon for symptoms that do not respond to medical management. Dystonia of childhood onset is treated by a pediatric neurologist cooperating with pediatricians and pediatric therapists.

Treatment Treatment for dystonia is usually directed towards management of the symptoms and depends on the type of dystonia. Dystonia that is associated or caused by known etiologies such as drugs, Wilson’s disease, or dopa-responsive dystonia may be improved by treating the underlying disease with resolution of symptoms. The various treatments available may be grouped into oral medications, botulinum toxin injections, and surgical modalities. Medications Various oral medications are available for the symptomatic treatment of dystonia. Among these are various medications that affect different neurochemical systems thought to be important in causing dystonia. Some patients with symptoms of early onset may have dystonia that responds dramatically to levodopa. Anticholinergics, dopamine depleting agents, benzodiazepines, baclofen, or atypical antipsychotics may be tried as well.

Recovery and rehabilitation Symptoms of dystonia may fluctuate over the course of years. The course of disease in any given individual can not be predicted. Some may improve spontaneously, whereas others may progress and spread to involve other body parts. Physical therapists may aid in the treatment of symptoms of dystonia. Treatment is focused on maintaining or improving the patient’s ability to walk. Occupational therapy may be helpful in improving hand use.

Clinical trials Several clinical trials are currently in effect for treatment of dystonia. The National Institutes of Health (NIH) and National Institutes of Neurological Diseases and Stroke (NINDS) are recruiting patients for trials examining the effect of different medications, botulinum toxin treatment, and surgical treatment for patients with dystonia. Studies are also ongoing to study the effect of electrical stimulation of the brain and nerves with magnetic fields to treat dystonia. Updated information on clinical trials can be found at the National Institutes of Health clinical trials website at www.clinicaltrials.org.

Prognosis The prognosis for dystonia depends on the distribution and the cause. The initial site of symptoms may predict the prognosis. Patients with symptoms that start in the

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All forms of dystonia impair normal movement and daily function to some degree. Dystonia can be worsened by stress and anxiety, whereas it may be relieved with relaxation and sleep. Symptoms may be improved by touching various parts of the body in a phenomenon called a “sensory trick.”

Dystonia

leg have a higher likelihood (90%) of progression to involve other body parts and become generalized. Patients with symptoms starting in the neck and later in onset have a much lower likelihood of spread. Most focal dystonias respond to medications or botulinum toxin. Refractory and generalized dystonia may require surgical management. Most patients have a normal life expectancy although with continued disabling symptoms.

Special concerns Dystonia in many cases is a chronic illness and due to the physical limitations and often disfiguring symptoms, may lead to feelings of depression or anxiety. These feelings may require treatment by a psychiatrist if severe enough. It is important for patients with dystonia to continue to be involved in community activities and social events. BOOKS

Bradley, Walter G., Robert Daroff, Gerald Fenichel, and C. David Marsden. Neurology in Clinical Practice. Newton, MA: Butterworth-Heinemann, 2000. Rowland, Lewis, ed. Merritt’s Textbook of Neurology. Philadelphia, PA: Lippincott Williams & Wilkins, 2000.

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Klein, C., and L. J. Ozelius. “Dystonia: clinical features, genetics, and treatment.” Current Opinion in Neurology 15 (2002): 491–497. Langlois, M., F. Richer, and S. Chouinard. “New Perspectives on Dystonia.” Canadian Journal of Neurological Sciences 30, Suppl. 1 (2003): S34–S44. Volkmann, J., and R. Benecke. “Deep Brain Stimulation for Dystonia: Patient Selection and Evaluation.” Movement Disorders 17 (2002): S112–S115. WEBSITES

Educational and social needs

Resources

PERIODICALS

NINDS Dystonias Information Page. National Institutes of Neurological Disorders and Stroke (NINDS). July 1, 2001. (June 7, 2004). ORGANIZATIONS

Dystonia Medical Research Foundation. 1 East Wacker Drive, Suite 2430, Chicago, IL 60601-1905. (312) 755-0198; Fax: (312) 803-0138. [email protected]/ . Worldwide Education & Awareness for Movement Disorders (WE MOVE). 204 West 84th Street, New York, NY 10024. (212) 875-8312 or (800) 437-6682; Fax: (212) 875-8389. [email protected]. .

Peter T. Lin, MD

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E Edrophonium see Cholinergic stimulants

❙ Electric personal assistive mobility devices

Definition Electric personal assistive mobility devices are powerassisted devices for mobility such as wheelchairs, scooters, and more recent innovations such as the Segway™ Human Transporter. These devices make everyday life easier for someone who is partially or completely immobile.

Description Currently there are approximately 160,000 people who use electric powered wheelchair and scooters in the United States alone. Of these, some 100,000 utilize wheelchairs and 60,000 use powered scooters. As baby boomers become senior citizens and mobility becomes more of a concern for this large population, the market for these aids is expected to increase. Industry estimates show the powered assistive device market as growing by about 7% each year through 2007. By 2007, sales of manual- and electricpowered wheelchairs and powered scooters is estimated to be $2.7 billion in the United States. Wheelchairs Electric wheelchairs appeared in the 1950s. Then, the less sophisticated mechanics of the chair produced a rougher and more jarring ride. Today’s models are better described as electronic chairs rather than electric chairs. Electronic circuitry allows for a control of speed and a precise control of direction. Many of today’s sophisticated powered wheelchairs conform to two basic styles. The first is called the traditional style and consists of a power source mounted behind or underneath the seat of the

wheelchair. As the name implies, the traditional unit looks very much like a manual wheelchair. The second design is known as a platform chair. In this design, the seating area, which can often be raised or lowered, sits on top of the power source. There are several groups of powered wheelchairs, based on the intended use. Wheelchairs designed strictly for indoor use have a smaller area between the wheels, allowing them to negotiate the tighter turns and more confined spaces of the indoor world. Other designs allow the electric wheelchair to be used both indoors and outdoors, on sidewalks, driveways, and hard, even surfaces. Finally, some electric wheelchairs are able to negotiate more rugged terrain such as uneven, stony surfaces. Wheelchairs meant for indoor and indoor/outdoor use conserve weight by reducing the size of the rechargeable batteries that deliver the power to the device. Outdoor models deliver more power, more speed, and can operate for a longer period of time, at the cost of a heavier wheelchair. Electric wheelchairs can also be classified according to the location of the wheels that drive the device. Rearwheel, mid-wheel, and front-wheel drive models are available. In a rear-wheel chair, the big wheels that drive the unit are positioned behind the rider’s center of gravity. This is the traditional chair design. In the mid-wheel design, the large wheels are positioned directly under the rider’s center of gravity. This offers a shorter turning radius, which can be useful in tight places. However, sudden stops can cause the chair to rock or pitch forward. Finally, the front-wheel drive chair has the large wheels in front of the rider’s center of gravity. This allows for a tight turning radius and even to climb over obstacles such as curbs. For people who are immobile, some wheelchairs are capable of adjusting the person’s position. Some chairs can recline and/or can tilt people back while they are still in the sitting position. Changes of position relieve pressure and can help lessen the development of skin irritation.

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This ability of fully paralyzed people to independently operate a wheelchair offers great potential in reducing the barriers that have prevented wheelchair users from participating fully in society. Innovations in electric-powered wheelchairs Construction materials used in wheelchair frames have reduced the weight of the chairs. Aluminum, stainless steel, and steel tubes are some of several materials that produce strength without excess weight. In 1993, a new powered wheelchair marketed as the Hoveround was launched. It has features of both a wheelchair and a scooter. The most unique features are the round base and single rear wheel, which allow the chair to be turned in a full circle on the spot. A relatively recent innovation is known as the pushrim-activated power-assisted wheelchair (PAPAW). This design uses motors and an electric battery to supply forward thrust or braking capabilities that complement similar manual actions of the user. A PAPAW is best suited to a user who can manually operate a wheelchair, but not very efficiently due to pain, insufficient arm strength, heart and/or lung trouble, or inability to maintain effective posture.

Roslyn Cappiello, a quadriplegic and president of the Omaha chapter of Mothers Against Drunk Driving. (AP/Wide World Photos. Reproduced by permission.)

Changing position can also help some people breathe more easily. Some powered wheelchairs are also capable of raising or lowering a person. This can make life easier by allowing the person to retrieve fallen objects and to reach higher-placed objects. Some wheelchairs can even raise the person to a standing position. This increases the range of tasks a person can accomplish. A wheelchair-bound person can wash dishes, clean windows, work at a counter, and put dishes away in a cupboard, as a few examples, thus reducing the need to modify a home. The controls to electric-powered wheelchairs vary depending on the mobility of the user. For those with arm function, a joystick can be used to propel the chair forwards or backwards, and to steer. Those who are paralyzed are able to perform these functions using a sip-and-puff setup via a straw. Some manufacturers even make voiceactivated and -responsive wheelchairs. 324

User demand is driving new designs for mobility devices that do not look like wheelchairs. Indeed, newer designs for wheelchairs are more similar to scooters than to the traditional design of the wheelchair. The impetus for this new design has been people’s desire for more independence and mobility, to the point of being able to mount curbs and travel over rough ground. The Independence 3000 IBOT Transporter (IBOT) can change the way it moves in response to varying terrain. The two pairs of large rear wheels can operate at different height, allowing for actions like the mounting of curbs. In fact, the front pair of wheels can ride up the rear set, enabling the two pairs of wheels to balance vertically on each other. Scooters Scooters are designed for people who are able to walk, but have difficulty walking significant distances. Examples include people with milder forms of cerebral palsy, multiple sclerosis, postpolio syndrome, and those who have had a stroke or who suffer from arthritis. Scooters are not designed for those who are absolutely immobile. Scooters consist of a seat mounted on a movable platform. The rider uses handle bars to maintain balance and to steer, although some scooters use electronics that control the steering instead of the operator. The seats are typically removable to allow the scooter to be easily transported in car, truck, or other vehicle. Scooters represent a hybrid between a manual and electric wheelchair. They appeal to those who do not have

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Other personal transport devices For many years, golf cart-style vehicles have provided transportation for elderly people. In retirement communities, carts can be an everyday part of the landscape, being used even on the roads of gated communities. As the population ages and decreased physical mobility affects more people, the popularity of electric carts may well grow. The Segway™ Human Transporter was introduced in the 1990s. It offers increased mobility for those with disabilities, but could also aid some persons who are unable to walk long distances. The machine operates on a principle called dynamic stabilization. Essentially, this means that the machine works in a manner similar to people’s sense of balance. When people standing on the machine shift their center of gravity forward, the machine moves forward. Shifting the center of gravity backward stops the machine. There is no accelerator or brake. While more of a curiosity than practical means of transport as of 2004, the transporter is an example of how increased mobility is possible in environments such as sidewalks and factories.

OTHER

Cooper, R. A., and R. Cooper. “Trends and Issues in Wheeled Mobility Technologies.” Center for Inclusive Design and Environmental Access. April 10, 2004 (June 2, 2004). . ORGANIZATIONS

Center for Inclusive Design and Environmental Access. School of Architecture and Design, University of Buffalo, Buffalo, NY 14214-3087. (716) 829-3485; Fax: (716) 829-3861. [email protected]. . Department of Rehabilitation Science and Technology. 420 Forbes Tower, University of Pittsburgh, Pittsburgh, PA 15260. (412) 383-6556; Fax: (412) 383-6597. [email protected]. . Worldwide Education & Awareness for Movement Disorders (WE MOVE). 204 West 84th Street, New York, NY 10024. (212) 875-8312 or (800) 437-MOV2 (6682); Fax: (212) 875-8389. [email protected]. .

Brian Douglas Hoyle, PhD

❙ Electroencephalography Definition

Electroencephalography, or EEG, is a neurological test that involves attaching electrodes to the head of a person to measure and record electrical activity in the brain over time.

Purpose The EEG, also known as a brain wave test, is a key tool in the diagnosis and management of epilepsy and other seizure disorders. It is also used to assist in the diagnosis of brain damage and diseases such as strokes, tumors, encephalitis, mental retardation, and sleep disorders. The results of the test can distinguish psychiatric conditions such as schizophrenia, paranoia, and depression from degenerative mental disorders such as Alzheimer’s and Parkinson’s diseases. An EEG may also be used to monitor brain activity during surgery to assess the effects of anesthesia. Additionally, it is used to determine brain status and brain death.

Resources BOOKS

Iezzoni, Lisa. When Walking Fails: Mobility Problems of Adults with Chronic Conditions. Berkeley: University of California Press, 2003. Karp, Gary. Life on Wheels: For the Active Wheelchair User. Sebastopol, CA: Patient-Centered Guides, 1999.

Precautions There are few adverse conditions associated with an EEG test. Persons with seizure disorders may experience seizures during the test in reaction to flashing lights or by deep breathing.

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the physical capability to power a manual wheelchair, but who do not need the electronic controls and various seating configurations that can be selected in some electric wheelchairs. For users who have the upper arm and body strength necessary to use one and also to hold themselves in a sitting position for a prolonged time, a scooter can represent a more economical alternative to a powered wheelchair. The basic setup of a scooter is known as the base unit. This consists of a frame made of steel or aluminum attached to a platform. Some units also have a windscreen as part of the unit. The seat post can be a permanent part of the frame, or may be detachable for easy transport. Scooters can be front-wheel drive or rear-wheel drive. The scooters with rear-wheel drive, which has a larger motor and a longer distance between the front and rear wheels, typically supply more power and so are useful for tasks like climbing hilly terrain. Front-wheel drive scooters have a smaller motor and so are more maneuverable in tight places such as indoor use. They can also be used outside on flat, paved surfaces. The choice of scooter depends on the user’s needs. Three- and four-wheeled scooters are also available. These provide more stability for users whose balance is faulty.

Electroencephalography

Description Before an EEG begins, a nurse or technologist attaches approximately 16–21 electrodes to a person’s scalp using an electrically conductive, washable paste. The electrodes are placed on the head in a standard pattern based on head circumference measurements. Depending on the purpose for the EEG, implantable, or invasive, electrodes are occasionally used. Implantable electrodes include sphenoidal electrodes, which are fine wires inserted under the zygomatic arch, or cheekbone. Depth electrodes, or subdural strip electrodes, are surgically implanted into the brain and are used to localize a seizure focus in preparation for epilepsy surgery. Once in place, even implantable electrodes do not cause pain. The electrodes are used to measure the electrical activity in various regions of the brain over the course of the test period. For the test, a person lies on a bed, padded table, or comfortable chair and is asked to relax and remain still while measurements are being taken. An EEG usually takes no more than one hour, although long-term monitoring is often used for diagnosis of seizure disorders. During the test procedure, a person may be asked to breathe slowly or quickly. Visual stimuli such as flashing lights or a patterned board may be used to stimulate certain types of brain activity. Throughout the procedure, the electroencephalography unit makes a continuous graphic record of the person’s brain activity, or brain waves, on a long strip of recording paper or computer screen. This graphic record is called an electroencephalogram. If the display is computerized, the test may be called a digital EEG, or dEEG. The sleep EEG uses the same equipment and procedures as a regular EEG. Persons undergoing a sleep EEG are encouraged to fall asleep completely rather than just relax. They are typically provided a bed and a quiet room conducive to sleep. A sleep EEG lasts up to three hours, or up to eight or nine hours if it is a night’s sleep. In an ambulatory EEG, individuals are hooked up to a portable cassette recorder. They then go about normal activities and take normal rest and sleep for a period of up to 24 hours. During this period, individuals and their family members record any symptoms or abnormal behaviors, which can later be correlated with the EEG to see if they represent seizures. An extension of the EEG technique, called quantitative EEG (qEEG), involves manipulating the EEG signals with a computer using the fast Fourier transform algorithm. The result is then best displayed using a colored gray scale transposed onto a schematic map of the head to form a topographic image. The brain map produced in this technique is a vivid illustration of electrical activity of the brain. This technique also has the ability to compare the similarity of the signals between different electrodes, a measurement known as spectral coherence. Studies have 326

Key Terms Encephalitis Inflammation of the brain. Fast Fourier transfer A digital processing of the recorded signal resulting in a decomposition of its frequency components. Ictal EEG An EEG done to determine the type of seizure characteristic of a person’s disorder. During this EEG, seizure medicine may be discontinued in an attempt to induce as seizure during the testing period. Sphenoidal electrodes Fine wire electrodes that are implanted under the cheek bones, used to measure temporal seizures. Subdural electrodes Strip electrodes that are placed under dura mater (the outermost, toughest, and most fibrous of the three membranes [meninges] covering the brain and spinal cord). They are used to locate foci of epileptic seizures prior to epilepsy surgery.

shown the value of this measurement in diagnosis of Alzheimer’s disease and mild closed-head injuries. The technique can also identify areas of the brain having abnormally slow activity when the data are both mapped and compared to known normal values. The result is then known as a statistical or significance probability map (SPM). This allows differentiation between early dementia (increased slowing) or otherwise uncomplicated depression (no slowing).

Preparation An EEG is generally performed as one test in a series of neurological evaluations. Rarely does the EEG form the sole basis for a particular diagnosis. Full instructions should be given to individuals receiving an EEG when they schedule their test. Typically, individuals taking medications that affect the central nervous system, such as anticonvulsants, stimulants, or antidepressants, are told to discontinue their prescription for a short time prior to the test (usually one or two days). However, such requests should be cleared with the treating physician. EEG test candidates may be asked to avoid food and beverages that contain caffeine, a central nervous system stimulant. They may also be asked to arrive for the test with clean hair that is free of spray or other styling products to make attachment of the electrodes easier. Individuals undergoing a sleep EEG may be asked to remain awake the night before their test. They may be given a sedative prior to the test to induce sleep.

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Electroencephalography

Woman undergoing an electroencephalogram (EEG). (Photograph by Catherine Pouedras. Science Photo Library, National Audubon Society Collection/Photo Researchers, Inc. Reproduced by permission.)

Aftercare If an individual has suspended regular medication for the test, the EEG nurse or technician should advise as to when to begin taking it again.

Risks Being off certain medications for one to two days may trigger seizures. Certain procedures used during EEG may trigger seizures in persons with epilepsy. Those procedures include flashing lights and deep breathing. If the EEG is being used as a diagnostic tool for epilepsy (i.e., to determine the type of seizures an individual is experiencing), this may be a desired effect, although the person needs to be monitored closely so that the seizure can be aborted if necessary. This type of test is known as an ictal EEG.

Normal results In reading and interpreting brain wave patterns, a neurologist or other physician will evaluate the type of brain waves and the symmetry, location, and consistency of brain wave patterns. Brain wave response to certain stimuli presented during the EEG test (such as flashing lights or noise) will also be evaluated.

The four basic types of brain waves are alpha, beta, theta, and delta, with the type distinguished by frequency. Alpha waves fall between 8 and 13 Hertz (Hz), beta are above 13 Hz, theta between 4 and 7 Hz, and delta are less than 4 Hz. Alpha waves are usually the dominant rhythm seen in the posterior region of the brain in older children and adults, when they are awake and relaxed. Beta waves are normal in sleep, particularly for infants and young children. Theta waves are normally found during drowsiness and sleep and are normal in wakefulness in children, while delta waves are the most prominent feature of the sleeping EEG. Spikes and sharp waves are generally abnormal; however, they are common in the EEG of normal newborns. Different types of brain waves are seen as abnormal only in the context of the location of the waves, a person’s age, and one’s state of consciousness. In general, disease typically increases slow activity such as theta or delta waves, but decreases fast activity such as alpha and beta waves. Not all decreases in wave activity are abnormal. The normal alpha waves seen in the posterior region of the brain are suppressed merely if a person is tense. Sometimes the addition of a wave is abnormal. For example, alpha

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rhythms seen in a newborn can signify seizure activity. Finally, the area where the rhythm is seen can be telling. The alpha coma is characterized by alpha rhythms produced diffusely, or, in other words, by all regions of the brain. Some abnormal beta rhythms include frontal beta waves that are induced by sedative drugs. Marked asymmetry in beta rhythms suggests a structural lesion on the side lacking the beta waves. Beta waves are also commonly measured over skull lesions such as fractures or burr holes, in an activity known as a breach rhythm. Usually seen only during sleep in adults, the presence of theta waves in the temporal region of awake, older adults has been tentatively correlated with vascular disease. Another rhythm normal in sleep, delta rhythms, may be recorded in a wakeful state over localized regions of cerebral damage. Intermittent delta rhythms are also an indication of damage of the relays between the deep gray matter and the cortex of the brain. In adults, this intermittent activity is found in the frontal region, whereas in children it is in the occipital region. The EEG readings of persons with epilepsy or other seizure disorders display bursts, or spikes, of electrical activity. In focal epilepsy, spikes are restricted to one hemisphere of the brain. If spikes are generalized to both hemispheres of the brain, multifocal epilepsy may be present. The EEG can be used to localize the region of the brain where the abnormal electrical activity is occurring. This is most easily accomplished using a recording method, or montage, called an average reference montage. With this type of recording, the signal from each electrode is compared to the average signal from all the electrodes. The negative amplitude (an upward movement) of the spike is observed for the different channels, or inputs, from the various electrodes. The negative deflection will be greatest as recorded by the electrode that is closest in location to the origin of the abnormal activity. The spike will be present but of reduced amplitude as the electrodes move farther away from the site producing the spike. Electrodes distant from the site will not record the spike occurrence. A final variety of abnormal result is the presence of slower-than-normal wave activity, which can either be a slow background rhythm or slow waves superimposed on a normal background. A posterior dominant rhythm of 7 Hz or less in an adult is abnormal and consistent with encephalopathy (brain disease). In contrast, localized theta or delta rhythms found in conjunction with normal background rhythms suggest a structural lesion. Resources BOOKS

Chin, W. C., and T. C. Head. Essentials of Clinical Neurophysiology, 3rd edition. London: ButterworthHeinemann, 2002. 328

Daube, J. R. Clinical Neurophysiology, 2nd edition. New York: Oxford University Press, 2002. Ebersole, J. S., and T. A. Pedley. Current Practice of Clinical Electroencephalography, 3rd Edition. Philadelphia: Lippincott Williams & Wilkins, 2002. Rowan, A. J., and E. Tolunsky. Primer of EEG. London: Butterworth-Heinemann, 2003. PERIODICALS

De Clercq, W., P. Lemmerling, S. Van Huffel, and W. Van Paesschen. “Anticipation of Epileptic Seizures from Standard EEG Recordings.” Lancet 361, no. 9361 (2003): 971–972. Harden, C. L., F. T. Burgut, and A. M. Kanner. “The Diagnostic Significance of Video-EEG Monitoring Findings on Pseudoseizure Patients Differs between Neurologists and Psychiatrists.” Epilepsia 44, no. 3 (2003): 453–456. Stepien, R. A. “Testing for Non-linearity in EEG Signal of Healthy Subjects.” Acta Experimental Neurobiology 62, no. 4 (2002): 277–281. Vanhatalo, S., M. D. Holmes, P. Tallgren, J. Voipio, K. Kaila, and J. W. Miller. “Very Slow EEG Responses Lateralize Temporal Lobe Seizures: An Evaluation of Non-invasive DC-EEG.” Neurology 60, no. 7 (2003): 1098–1104. ORGANIZATIONS

American Association of Electrodiagnostic Medicine. 421 First Avenue SW, Suite 300 East, Rochester, MN 55902. (507) 288-0100; Fax: (507) 288-1225. [email protected]. . American Board of Registration of EEG and EP Technologists. PO Box 891663, Longwood, FL 32791. (407) 788-6308. . American Society of Electroneurodiagnostic Technologists Inc., 204 W. 7th Carroll, IA 51401. (712) 792-2978. . Epilepsy Foundation. 4351 Garden City Drive, Landover, MD 20785-7223. (800) 332-1000 or (301) 459-3700. . Joint Review Committee on Electroneurodiagnostic Technology. 3350 South 198th Rd., Goodson, MO 656599110. (417) 253-5810. . OTHER

Electroencephalography. Hofstra University. April 27, 2003 (February 18, 2004). . Bergey, Gregory K., and Piotr J. Franaszczuk. “Epileptic Seizures Are Characterized by Changing Signal Complexity.” April 17, 2003 (February 18, 2004). . Rutherford, Kim, M.D. “EEG (Electroencephalography).” Kid’s Health For Parents. June 2001 (February 18, 2004). . Epilepsy Information: Electroencephalography. National Society for Epilepsy. September 2002 (February 18,

GALE ENCYCLOPEDIA OF NEUROLOGICAL DISORDERS

L. Fleming Fallon, Jr., MD, DrPH

• ataxias • myasthenias • inflammatory myopathies

Precautions

❙ Electromyography Definition

Electromyography (EMG) is an electrical recording of muscle activity that aids in the diagnosis of neuromuscular disease, which affects muscle and peripheral nerves.

No special precautions are needed for this test. Persons with a history of bleeding disorder should consult with their treating physician before the test. If a muscle biopsy is planned as part of the diagnostic workup, EMG should not be performed at the same site, as it may affect the microscopic appearance of the muscle. Also, persons on blood thinners should relay this information to the physician performing the EMG.

Purpose Muscles are stimulated by signals from nerve cells called motor neurons. This stimulation causes electrical activity in the muscle, which in turn causes contraction. A needle electrode inserted into the muscle and connected to a recording device detects this electrical activity. Together, the electrode and recorder are called an electromyography machine. EMG can determine whether a particular muscle is responding appropriately to stimulation, and whether a muscle remains inactive when not stimulated. EMG is performed most often to help diagnose different diseases causing weakness. Although EMG is a test of the motor system, it may help identify abnormalities of nerves or spinal nerve roots that may be associated with pain or numbness. Other symptoms for which EMG may be useful include atrophy, stiffness, fasciculation (muscle twitching), cramp, deformity, and spasticity. EMG results can help determine whether symptoms are due to a muscle disease or a neurological disorder, and, when combined with clinical findings, usually allow a confident diagnosis. EMG can help diagnose many muscle and nerve disorders, including: • muscular dystrophy • congenital myopathies • mitochondrial myopathies • metabolic myopathies

Description During an EMG test, a fine needle is inserted into the muscle to be tested. This may cause some discomfort, similar to that of an injection. Recordings are made while the muscle is at rest, and then during the contraction. The person performing the test may move the limb being tested, and direct the patient to move it with various levels of force. The needle may be repositioned in the same muscle for further recording. Other muscles may be tested as well. A typical session lasts from 30–60 minutes, with individual muscles usually studied for a period of two to five minutes. A slightly different test, the “nerve conduction velocity test,” is often performed at the same time with the same equipment. In this test, stimulating and recording electrodes are used and small electrical shocks are applied to measure the ability of the nerve to conduct electrical signals. This test may cause mild tingling and discomfort similar to a mild shock from static electricity. Evoked potentials may also be performed for additional diagnostic information. Nerve conduction velocity and evoked potential testing are especially helpful when pain or sensory complaints are more problematic than weakness.

Preparation No special preparation is needed. The doctor supervising and interpreting the test should be given information about the symptoms, medical conditions, suspected diagnosis, neuroimaging studies, and other test results.

• myotonias • peripheral neuropathies • radiculopathies • nerve lesions

Aftercare Minor pain and bleeding may continue for several hours after the test. The muscle may be tender for a day or two.

• amyotrophic lateral sclerosis • polio • spinal muscular atrophy • Guillain-Barré syndrome

Risks There are no significant risks to this test, other than those associated with any needle insertion (pain, bleeding, bruising, or infection).

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Electromyography

2004). .

Electromyography Patient undergoing electromyography. (Custom Medical Stock Photo. Reproduced by permission.)

Key Terms Motor neurons Nerve cells that transmit signals from the brain or spinal cord to the muscles. Motor unit action potentials Spikes of electrical activity recorded during an EMG that reflect the number of motor units (motor neurons and the muscle fibers they transmit signals to) activated when the patient voluntarily contracts a muscle.

Normal results There should be some brief EMG activity during needle insertion. This activity may be increased in diseases of the nerve and decreased in long-standing muscle disorders in which muscle tissue is replaced by fibrous tissue or fat. Muscle tissue normally shows no EMG activity when at rest or when moved passively by the examiner. When the patient actively contracts the muscle, spikes (motor unit action potentials) should appear on the recording screen, reflecting the electrical activity within. As the muscle is 330

contracted more forcefully, more groups of muscle fibers are recruited or activated, causing more EMG activity. The interpretation of EMG results is not a simple matter, requiring analysis of the onset, duration, amplitude, and other characteristics of the spike patterns. Electrical activity at rest is abnormal; the particular pattern of firing may indicate denervation (for example, a nerve lesion, radiculopathy, or lower motor neuron degeneration), myotonia, or inflammatory myopathy. Decreases in the amplitude and duration of spikes are associated with muscle diseases, which also show faster recruitment of other muscle fibers to compensate for weakness. Increases in the amplitude and duration of the spikes are typical of nerve diseases in which some degree of reinnervation (repair by new nerve connections to muscle) has occurred. Recruitment is reduced in nerve disorders. Resources BOOKS

Basmajian, J., and C. DeLuca. Muscles Alive: Their Function Revealed by Electromyography, 5th ed. Baltimore: Williams & Wilkins, 1985.

Richard Robinson

GALE ENCYCLOPEDIA OF NEUROLOGICAL DISORDERS

Definition

Empty sella syndrome is the appearance, by radiograph (x ray) of the skull, that the sella turcica, which normally contains the pituitary gland, is empty.

Description Sella turcica is Latin for “Turkish saddle,” which roughly describes the U–shaped appearance of this bony pocket when seen by x ray. It is a concavity in the middle of the sphenoid bone measuring about 1.5 × 1.0 × 0.5 cm. The sphenoid bone forms a portion of the base of the skull just behind the eyes, at about the midpoint and just below the cerebral hemispheres. The pituitary gland has a bulbous shape, extending on a stalk below the hypothalamus. The pituitary normally completely fills the sella turcica. The subarachnoid space, filled with cerebrospinal fluid (CSF), surrounds the pituitary stalk. The dura mater (see Meninges) normally extends away from the bony upper portion of the sella turcica forming a barrier between the subarachnoid space and the pituitary gland below. This barrier formed by the dura mater surrounding the top of the pituitary gland is known as the diaphragma sella. In most cases when an empty sella is seen by x ray, the sella turcica is not truly empty. In fact, CSF has entered the space normally occupied by the pituitary and has compressed the gland against the wall of the sella. A truly empty sella, i.e., missing pituitary gland, is rare.

Demographics The true incidence of empty sella syndrome in the population is not known. However, statistics collected from autopsies have shown that an empty sella is found as an incidental finding in anywhere from 5% to 25% of cases. These do not include cases in which the pituitary gland was surgically removed or irradiated. Most cases of empty sella syndrome are seen in middle–aged, obese women, who often have hypertension. Children with empty sella syndrome are more often symptomatic, which most often manifests as growth hormone deficiency. About half of children with growth hormone deficiency are found to have an empty sella, but only 2% of children with normal pituitary function have the finding.

Causes and symptoms Primary empty sella syndrome is thought to be congenital (present at birth) in most cases, and is caused by a failure or opening of the diaphragma sella. This may be an

Key Terms Cerebrospinal fluid The clear, normally colorless fluid that fills the brain cavities (ventricles), the subarachnoid space around the brain, and the spinal cord and acts as a shock absorber. Hypopituitarism A condition characterized by underactivity of the pituitary gland. Pituitary gland The most important of the endocrine glands (glands that release hormones directly into the bloodstream), the pituitary is located at the base of the brain. Sometimes referred to as the “master gland,” it regulates and controls the activities of other endocrine glands and many body processes including growth and reproductive function. Also called the hypophysis.

accidental occurrence, with no known triggering or causative factors. In some cases the sella turcica may grow larger than normal. Secondary empty sella (acquired) may be caused by a medical procedure, such as surgery or radiation for a pituitary tumor. Disease or trauma may also reduce the size of the pituitary, or eliminate it completely. Abnormally low production of one or more pituitary hormones is known as hypopituitarism. A specific type of acquired empty sella syndrome associated with hypopituitarism, known as Sheehan’s syndrome, is caused by infarction (loss of blood supply) of the pituitary brought on by shock or hemorrhage after labor and delivery. In cases of acquired empty sella, the condition is a byproduct of some other process. Probably less than 10% of individuals with primary empty sella syndrome have some symptoms of hypopituitarism. Symptoms related to secondary empty sella syndrome would be those of the underlying cause, except in the case of empty sella syndrome due to trauma. Hypopituitarism can result in one or more of the following: • Hypothyroidism. Decreased production of the thyroid gland, which can result in diminished metabolism, intolerance of cold temperatures, fatigue, mental and physical sluggishness, constipation, muscle aches, dry skin, and dry hair. • Hypogonadism. Decreased production of sex hormones, which can result in loss of pubic hair, decreased sex drive, impotence in men, and amenorrhea (absence of menstrual cycle) in women.

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Empty sella syndrome

❙ Empty sella syndrome

Encephalitis and meningitis

• Hypoadrenalism. Decreased production of the adrenal gland, which can result in low blood pressure and hypoglycemia (low blood sugar).

Diagnosis Other than those cases detected directly at autopsy (usually incidentally), empty sella syndrome is always diagnosed by some type of imaging study of the brain (x ray, CT scan, or MRI). Again, in many of these cases the empty sella is detected as a coincidental finding on an imaging study ordered for some other reason. Only occasionally is the diagnosis made because empty sella syndrome was suspected from some type of endocrinological abnormality suggesting hypopituitarism.

Gilroy, John. Basic Neurology, 3rd ed. New York: McGrawHill, 2000. pp. 521-523. Reinhardt, Shelley, et al, eds. Basic & Clinical Endocrinology, 6th ed. Philadelphia: McGraw Hill, 2001. pp. 128-129. Wilson, Jean D., et al, eds. Williams Textbook of Endocrinology, 9th ed. Philadelphia: W.B. Saunders Company, 1998.. OTHER

Empty Sella Syndrome Information Page. The National Institute of Neurological Disorders and Stroke. (September 10, 2003). http://www.ninds.nih.gov/ health_and_medical/disorders/emptysella.htm.

Scott J. Polzin, MS, CGC

Treatment Treatment of symptomatic empty sella syndrome would typically involve replacement therapy for any deficient hormones. For instance, hypothyroidism would require treatment with synthetic thyroid hormone, hypoadrenalism could be treated with steroids (cortisol), and hypogonadism might require sex hormone replacement therapy. Treatment of endocrinological dysfunction can be especially difficult because of the complicated way in which the many hormones of the body interact with and affect each other. In addition, all treatments for empty sella syndrome would be symptomatic treatments; there is no method to restore the pituitary gland to its normal size.

Prognosis In most cases in which hypopituitarism accompanies empty sella syndrome, treatment for the symptoms would be lifelong. In all cases in which disease or medical intervention has reduced or eliminated the pituitary gland, there is no method of completely restoring normal pituitary function. Replacement therapies are effective when well-managed. However, even someone with optimum therapy is unlikely to feel completely “well,” in relation to normal pituitary function, all of the time.

Special concerns Symptoms of empty sella syndrome may be subtle, and may mimic other conditions. Since an accurate diagnosis of empty sella syndrome requires imaging studies of the brain, there is a risk that the condition could be misdiagnosed, or go undiagnosed. Resources BOOKS

DeMyer, William. Neuroanatomy, 2nd ed. Baltimore: Williams & Wilkins, 1998. pp. 312-316. 332

❙ Encephalitis and meningitis Definition

Encephalitis is an acute inflammatory process that affects brain tissue and is almost always accompanied by inflammation of the adjacent meninges (tissues lining the brain). There are many types of encephalitis, most of which are caused by viral infections. Meningitis is an inflammation of the membranes (meninges) that surround the brain and spinal cord. Meningitis may be caused by many different viruses and bacteria, or by diseases that can cause inflammation of tissues of the body without infection (such as systemic lupus erythematosus). Viral meningitis is sometimes called aseptic meningitis to indicate it is not the result of a bacterial infection.

Description Encephalitis can be divided into two forms, primary and secondary encephalitis, according to the two methods by which the viruses infect the brain. Primary encephalitis occurs when a virus directly invades the brain and spinal cord. Primary encephalitis can happen to people at any time of the year (sporadic encephalitis), or can be part of an outbreak (epidemic encephalitis). Secondary, or post-infectious encephalitis occurs when a virus first infects another organ and secondarily enters the brain. Meningitis is an inflammation of the membranes that surround the brain and spinal cord, and may be caused by many different viruses and bacteria, or by non-infectious inflammatory diseases. Encephalitis is a distinct disease from meningitis, although, clinically, the two often share signs and symptoms of inflammation of the meninges.

GALE ENCYCLOPEDIA OF NEUROLOGICAL DISORDERS

Determining the true incidence of encephalitis in the United States is difficult because reporting policies are neither standardized nor rigorously enforced. Several thousand cases of viral encephalitis are reported yearly. HSE (herpes simplex encephalitis), the most common cause of sporadic encephalitis in other western countries, is still relatively rare in the United States, with an overall incidence of two cases per one million persons per year. Arboviruses (viruses transmitted to humans by bloodsucking insects such as mosquitoes and ticks) are the most common causes of episodic encephalitis. These statistics may be misleading because most people bitten by arbovirus-infected insects do not develop clinical disease, and only 10% of those develop overt encephalitis. Among less common causes of viral encephalitis, varicella-zoster encephalitis (a complication of the condition commonly known as shingles) has an incidence of one in 2000 infected people. Internationally, Japanese virus encephalitis (JE), occurring principally in Japan, Southeast Asia, China, and India, is the most common viral encephalitis outside the United States. In 1995, there were 5755 cases of bacterial meningitis reported in United States. This is a dramatic decrease from the 12,920 cases reported in 1986, probably due to the decrease in Haemophilus influenzae meningitis since the introduction of the Hib vaccine. The occurrences by infectious agents in 1995 are as follows: • Streptococcus pneumoniae: 1.1 per 100,000 persons • Neisseria meningitides: 0.6 per100,000 persons • Streptococcus: 0.3 per 100,000 persons • Listeria monocytogenes: 0.2 per 100,000 persons • Haemophilus influenzae: 0.2 per 100,000 persons The incidence of meningitis in newborns has shown no significant change in the last 25 years. Viral meningitis is the most common form of aseptic meningitis and, since the introduction of the mumps vaccine, is caused by enteroviruses in up to 85% of cases. The incidence of encephalitis is more difficult to estimate because of difficulty in establishing the diagnosis. One report estimates an incidence of one in 500–1,000 infants and in the first six months of life.

Causes and symptoms Causes The causes of encephalitis are usually infectious, but may also be due to some noninfectious causes. Three broad categories of viruses—herpes viruses, viruses responsible for childhood infections, and arboviruses

Key Terms Arboviruses Viruses harbored by arthropods (mosquitoes and ticks) and transferred to humans by their bite. Arboviruses are one cause of encephalitis. Electroencephalogram A procedure that uses electrodes on the scalp to record electrical activity of the brain. Used for detection of epilepsy, coma, and brain death. Encephalitis Inflammation of the brain. Meningitis Inflammation of the meninges, the membranes that surround the brain and spinal cord. Pathogen A disease-causing organism. Seizure A convulsion, or uncontrolled discharge of nerve cells that may spread to other cells throughout the brain.

(viruses harbored by mosquitoes and ticks, and transferred through their bite)—typically trigger encephalitis. ENCEPHALITIS AND HERPES VIRUSES Some herpes viruses that cause common infections may also cause encephalitis. These include:

• Herpes simplex virus. There are two types of herpes simplex virus (HSV) infections. HSV type 1 (HSV-1) causes cold sores or fever blisters around the mouth. HSV type 2 (HSV-2) causes genital herpes. HSV is the most common cause of sporadic encephalitis, with HSV-1 being the more common culprit. When untreated, the mortality rate from herpes simplex encephalitis is between 60–80%. That number drops to 15–20% with treatment. • Varicella-zoster virus. This virus is responsible for chicken pox and shingles. It can cause encephalitis in adults and children, but the cases tend to be mild. • Epstein-Barr virus. This herpes virus causes infectious mononucleosis. If encephalitis develops, it’s usually mild, but more severe forms can result in death in up to 8% of cases. ARBOVIRUSES The mosquito season varies according to geographic location. Arbovirus transmission, therefore, also varies according to season, the cycle of viral transmission, and local climatic conditions. Six encephalitis disease groups caused by arboviruses are monitored by the United States Centers for Disease Control (CDC) and include:

• St. Louis encephalitis • West Nile encephalitis

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Demographics

Encephalitis and meningitis

skull in infants, and irritability. More severe or late symptoms include loss of consciousness, seizures, muscle weakness, or sudden severe dementia.

• Powassan encephalitis • Eastern equine encephalitis • Western equine encephalitis • California serogroup viral encephalitis, which includes infections with the following viruses: La Crosse, Jamestown Canyon, snowshoe hare, trivittatus, Keystone, and California encephalitis viruses. OTHER CAUSES OF ENCEPHALITIS Bacterial pathogens (disease-causing organisms), such as rickettsial disease, mycoplasma, and cat scratch disease, are rare, but often involve inflammation of the meninges. Encephalitis can be due to parasites and fungi. Insects, such as mosquitoes in the eastern and southeastern United States can also spread encephalitis. CAUSES OF MENINGITIS Viral meningitis is the most common infection of the Central Nervous System (CNS). It most frequently occurs in children younger than one year of age. Enteroviruses (viruses that causes infections of the gastrointestinal tract) are the most common causative agent and are a frequent cause of febrile illnesses in children. Other viral pathogens include paramyxoviruses, herpes, influenza, rubella, and adenovirus. Meningitis may occur in up to half of children younger than three months with enteroviral infections. Enteroviral infections can occur any time during the year, but are normally associated with outbreaks in the summer and fall. Viral infections cause an inflammatory response, but to a lesser degree than bacterial infections. Damage from viral meningitis may be due to an associated encephalitis and increased intracranial pressure.

Bacterial meningitis is fairly uncommon, but can be extremely serious. There are two main types of bacterial meningitis, which cause most of the reported bacterial cases: meningococcal and pneumococcal. Haempohilus influenzae type b (Hib), which was recently a major cause of bacterial meningitis, has now been almost eliminated by the vaccination of infants. The most common causative organisms in the first month of life are Escherichia coli and group B streptococci. Listeria monocytogenes infection also occurs in patients in this age range and accounts for 5–10% of cases. In people older than two months, S. pneumoniae and N. meningitides currently cause the majority of the cases of bacterial meningitis. H. influenzae may still occur, especially in children who have not received the Hib vaccine. Symptoms Symptoms of encephalitis include sudden fever, headache, vomiting, heightened sensitivity to light, stiff neck and back, confusion and impaired judgment, drowsiness, weak muscles, a clumsy and unsteady gait (manner of walking), bulging in the soft spots (fontanels) of the 334

Symptoms of meningitis, which may appear suddenly, often include high fever, severe and persistent headache, stiff neck, nausea, and vomiting. Changes in behavior such as confusion, sleepiness, and difficulty waking up are extremely important symptoms and may require emergency treatment. In infants, symptoms of meningitis may include high-pitched cry, moaning cry, whimpering, dislike of being handled, fretfulness, arching of the back, neck retraction, blank, staring expression, difficulty in waking, lethargia, fever, cold hands and feet, refusing to feed or vomiting, pale, blotchy skin color. In adults, symptoms of meningitis may include vomiting, headache, drowsiness, seizures, high temperature, joint pain, stiff neck, and aversion to light. Arboviral infections may be asymptomatic or may result in illnesses of variable severity. Arboviral meningitis is characterized by fever, headache, and stiff neck. Arboviral encephalitis is characterized by fever, headache, and altered mental status that ranges from confusion to coma. Signs of brain dysfunction such as numbness or paralysis, cranial nerve palsies, visual or hearing deficits, abnormal reflexes, and generalized seizures may also be present.

Diagnosis Encephalitis or meningitis is suspected by a physician when the symptoms described above are present. The physician diagnoses encephalitis or meningitis after a careful examination and testing. The examination includes special maneuvers to detect signs of inflammation of the membranes that surround the brain and spinal cord (meninges). Tests that are used in the evaluation of individuals suspected of having encephalitis or meningitis include blood counts, blood cultures, coagulation studies, bacterial antigen studies of urine and serum, brain scanning, and spinal fluid analysis. The most common method of diagnosing encephalitis and meningitis is to analyze the cerebrospinal fluid surrounding the brain and spinal cord. A needle inserted into lower spine extracts a sample of fluid for laboratory analysis, which may reveal the presence of an infection or an increased white blood cell count, a signal that the immune system is fighting an infection. The cerebrospinal fluid may also be slightly bloody if small hemorrhages have occurred. Diagnosis of herpes simplex encephalitis can be difficult, but advances using sensitive DNA methods have allowed detection of the virus in spinal fluid. Electroencephalography (EEG) measures the waves of electrical activity produced by the brain. It is often used

GALE ENCYCLOPEDIA OF NEUROLOGICAL DISORDERS

Encephalitis and meningitis Occipital lobes of brain with acute meningitis. Dura mater has been reflected from surface of brain, revealing intensely discolored red (hyperemic) arachnoid mater and subarachnoid pus (white-gray purulent material). The patient, a three-and-ahalf-year-old boy, was well except for an upper respiratory infection with cough one day prior to death. (Joseph R. Siebert. photograph. © Custom Medical Stock Photo. Reproduced by permission.)

to diagnose and manage seizure disorders. A number of small electrodes are attached to the scalp. The patient remains still during the test and at times may be asked to breathe deeply and steadily for several minutes or to stare at a patterned board. At times, a light may be flashed into eyes. These actions are meant to stimulate the brain. The electrodes pick up the electrical impulses from brain and send them to the EEG machine, which records the brain waves on a moving sheet of paper. An abnormal EEG result may suggest some of diseases, but a normal result does not rule them out. Brain imaging, using computed tomography (CT) or magnetic resonance imaging (MRI) may reveal swelling of brain. These techniques may reveal another condition with signs and symptoms that are similar to encephalitis, such as a concussion. Rarely, if diagnosis of herpes simplex encephalitis isn’t possible using DNA methods or by CT or MRI scans, a physician may take a small sample of the brain tissue, or biopsy, for analysis to determine if the virus is present. Physicians usually attempt treatment with antiviral medications before suggesting brain biopsy.

Blood testing can confirm the presence of West Nile virus in the body by drawing a sample of blood for laboratory analysis. When infected with West Nile virus, an analysis of blood sample may show a rising level of an antibody against the virus, a positive DNA test for the virus or a positive virus culture.

Treatment team The treatment team may include a pediatrician or a general practitioner, an infectious disease specialist and/or a critical care specialist, a neurosurgeon, a neurologist or a neonatologist. Others professionals may give support during hospitalization for intravenous antibiotics or other specific procedures.

Treatment Treatment for meningitis depends on the cause and on the symptoms. Antiviral medications may be used if a virus is involved. Antibiotics are prescribed for bacterial infections. If the causative organism is unknown, antibiotic regimes can be based on the child’s age. In infants

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Encephalitis and meningitis

Causes of Encephalitis

How Spread

Enteroviruses

Contact with body fluids

Herpes simplex virus

Person to person contact

HIV (human immunodeficiency virus)

When an infected person's blood or body fluids are introduced into the bloodstream of a healthy person

Arboviruses

Bites from mosquitoes that pick up the virus from infected birds, chipmunks, squirrels, or other animals

Animal-borne illnesses

Bites from infected animals such as cats, dogs, and bats

(Illustration created by Frank Forney.)

aged 30 days or younger, ampicillin is usually prescribed along with an aminoglycoside or a cephalosporin (cefotaxime) medication. In children aged 30–60 days, ampicillin and a cephalosporin (ceftriaxone or cefotaxime) can also be used. However, since S. pneumoniae occasionally occurs in this age range, vancomycin should be part of treatment instead of ampicillin. In older children, cephalosporin or ampicillin plus chloramphenicol can be used. Often, rifampicin is given (in meningococcal bacterial meningitis cases) as a preventative measure to roommates, close family members, or others who may have come in contact with an infected person. In addition, anticonvulsant medications may be used if there are seizures. Corticosteroids may be needed to reduce brain swelling and inflammation. Dexamethasone is usually indicated for children with suspected meningitis who are older than six weeks and is recommended for treatment of infants and children with H. influenzae meningitis. Sedatives may be needed for irritability or restlessness and over-the-counter medications may be used for fever and headache. Until a bacterial cause of CNS inflammation is excluded, the treatment should include parenteral (given by injection) antibiotics. Treatment with a third-generation cephalosporin antibiotic, such as cefotaxime sodium 336

(Claforan) or ceftriaxone sodium (Rocephin), is usually recommended. Vancomycin (Lyphocin, Vancocin, Vancoled) should be added in geographic areas where strains of S. pneumoniae resistant to penicillin and cephalosporins have been reported. Encephalitis can be difficult to treat because the viruses that cause the disease generally don’t respond to many medications. The exceptions are herpes simplex virus and varicella-zoster virus, which respond to the antiviral drug acyclovir, and is usually administered intravenously in the hospital for at least ten days. Treatment is available for many symptoms of encephalitis. Patients with headache should rest in a quiet, dark environment and take analgesics. Narcotic therapy may be needed for pain relief; however, medication induced changes in level of consciousness should be avoided. Anticonvulsant medication and anti-inflammatory drugs to reduce swelling and pressure within the skull are usually prescribed. Otherwise, treatment mainly consists of rest and a healthy diet including plenty of liquids.

Recovery and rehabilitation As opposed to many untreatable neurological conditions, encephalitis and meningitis are diseases that, given the adequate treatment described above, often resolve with

GALE ENCYCLOPEDIA OF NEUROLOGICAL DISORDERS

Clinical trials The National Institute of Allergy and Infectious Diseases (NIAID) and the National Institute of Neurological Disorders and Stroke (NINDS) support and conduct research on encephalitis and meningitis. Much of this research is aimed at learning more about the cause(s), prevention, and treatment of these disorders. Ongoing clinical trials as of early 2004 include: • Valacyclovir for long-term therapy of Herpes simplex encephalitis; IVIG—West Nile encephalitis: Safety and Efficacy; Structure of the Herpes Simplex Virus Receptor; sponsored by National Institute of Allergy and Infectious Diseases • Natural History of West Nile Virus Infection; OmrIgG-am™ for Treating Patients with or at High Risk for West Nile Virus Disease; sponsored by Warren G. Magnuson Clinical Center • Intrathecal Gemcitibine to Treat Neoplastic Meningitis; Intrathecal Gemcitabine in Treating Patients with Cancer and Neoplastic Meningitis; sponsored by Baylor College of Medicine Updated information on clinical trials can be found at the National Institutes of Health clinical trials website at www.clinicaltrials.org.

varies with the age of the person, clinical condition, and infecting organism.

Special concerns A person’s exposure to mosquitoes and other insects that harbor arboviruses can be reduced by taking precautions when in a mosquito-prone area. Insect repellents containing DEET provide effective temporary protection form mosquito bites. Long sleeves and pants should be worn when outside during the evening hours of peak mosquito activity. When camping outside, intact mosquito netting over sleeping areas reduces the risk of mosquito bites. Communities also employ large-scale spraying of pesticides to reduce the population of mosquitoes, and encourage citizens to eliminate all standing water sources, such as in bird baths, flower pots, and tires stored outside to eliminate possible breeding grounds for mosquitoes. Although large epidemics of meningococcal meningitis do not occur in the United States, some countries experience large, periodic outbreaks. Overseas travelers should check to see if meningococcal vaccine is recommended for their destination. Travelers should receive the vaccine at least one week before departure, if possible. A vaccine to prevent meningitis due to S. pneumoniae (also called pneumococcal meningitis) can also prevent other forms of infection due to S. pneumoniae. The pneumococcal vaccine is not effective in children under two years of age, but it is recommended for all individuals over 65 years of age and younger people with certain chronic medical conditions. Resources

Prognosis The prognosis for encephalitis varies. Some cases are mild, short and relatively benign and patients have full recovery. Other cases are severe, and permanent impairment or death is possible. The acute phase of encephalitis may last for one to two weeks, with gradual or sudden resolution of fever and neurological symptoms. Neurological symptoms may require many months before full recovery. Prognosis for people with viral meningitis is usually good. With early diagnosis and prompt treatment, most patients recover from meningitis. However, in some cases, the disease progresses so rapidly that death occurs during the first 48 hours, despite early treatment. Permanent neurological impairments including memory, speech, vision, hearing, muscle control, and sensation difficulties can occur in people who survive severe cases of meningitis and encephalitis. The prognosis for appropriately treated meningitis has improved, but there is still a 5% mortality rate and significant morbidity (lasting impairment). The prognosis

BOOKS

Kandel, Eric R. Principles of Neural Science. New York: McGraw-Hill/Appleton & Lange, 2000. Kolb, Bryan, and Ian Q. Whishaw. Introduction to Brain and Behavior. New York: W. H. Freeman & Co, 2001. Roos, Karen L. Meningitis: 100 Maxims. London: Edward Arnold, 1996. PERIODICALS

Chandesris, M. O., et al. “A case of Influenza virus encephalitis in south of France.” Rev Med Interne 25 (2004): 78–82. Kurt-Jones, E. A., et al. “Herpes simplex virus 1 interaction with Toll-like receptor 2 contributes to lethal encephalitis.” Proc Natl Acad Sci USA (2004): 1315–1320. OTHER

Information on Arboviral Encephalitides. Centers for Disease Control and Prevention. (April 10, 2004). NINDS Encephalitis and Meningitis Information Page. National Institutes of Neurological Disorders and Stroke. (April 10, 2004). Top 20 Meningitis FAQs. Meningitis Foundation of America. (April 10, 2004).

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complete recovery. It is very important that the disease’s cause is promptly identified and treated before any complication is irreversibly established. Physical and speech therapy are often helpful when neurological deficits remain, as are occupational therapists and audiologists.

Encephalitis lethargica

ORGANIZATIONS

Meningitis Foundation of America, Inc. 7155 Shadeland Station Suite 190, Indianapolis, Indiana 46256-3922. (317) 595-6383 or (800) 668-1129; Fax: (317) 595-6370. [email protected]. . National Institute of Allergy and Infectious Diseases (NIAID). 31 Center Drive, Rm. 7A50 MSC 2520, Bethesda, Maryland 20892-2520. (301) 496-5717. . Centers for Disease Control and Prevention (CDC), Division of Vector-Borne Infectious Diseases. P.O. Box 2087, Fort Collins, Colorado 80522. (800) 311-3435. dvbid@ cdc.gov. .

Bruno Marcos Verbeno Iuri Drumond Louro, M.D., Ph.D.

❙ Encephalitis lethargica

The latest epidemic is a result of the relaxed surveillance for the disease that happened with the near-eradication of the disease in the 1960s. As of 2004, the disease is a threat to more than 60 million people in 36 sub-Saharan African countries. In 1999, nearly 45,000 cases were reported, according to the World Health Organization (WHO). These cases represent individuals who were able to seek treatment and receive a definitive diagnosis at local health care centers. The actual number of cases was likely much higher, with estimates ranging from 300,000–500,000 cases actually occurring. In Africa, the disease occurs primarily in rural areas, where health care is least available. Poverty and encephalitis lethargica are associated with one another.

Causes and symptoms

Definition

Encephalitis lethargica is an inflammation of the brain caused by two trypanosomes (microscopic protozoan parasites). The illness, which can be fatal, is transmitted from one infected person to another by the tsetse fly. While it can occur globally, encephalitis lethargica is especially prevalent in Africa.

Description Encephalitis lethargica is a vector-borne disease, meaning it is transmitted to a susceptible person by a living creature. The tsetse fly lives in moist vegetation near lakes and rivers and in grassy areas. People living near these regions are most susceptible the bite of a tsetse fly infected with the trypasosomes that cause encephalitis lethargica. The disease is also known as African trypanosomiasis, sleeping sickness, sleepy sickness, and von Economo’s disease. Another form of the trypanosomeborne disease that occurs in North, Central, and South America is called Chagas disease. Other subspecies of the trypanosome parasite can infect animals such as cattle, who can also harbor the trypanosomes that are infectious to humans.

Demographics The form of encephalitis lethargica known as African trypanosomiasis occurs only in the sub-Saharan area of Africa. Tsetse flies are endemic in this region. However, for as yet unknown reasons, there are regions where tsetse flies are found, but the disease is absent. There have been several epidemics in Africa in the nineteenth and twentieth centuries. From 1896–1906, Uganda and the Congo

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basin were affected. A more wide-ranging epidemic occurred in 1920. Finally, an epidemic that began in 1970 is still occurring.

The disease is caused by Trypanosoma brucei gambiense and Trypanosoma brucei rhodesiense. The first species is found in central and West Africa. The infection is chronic; it persists for months or years with no display of symptoms. When they do emerge, the disease is at an advanced stage and the symptoms are more severe. T. brucei rhodesiense is found primarily in southern and eastern Africa. It causes an infection whose symptoms appear quickly (acute infection). This disease is more severe. Fortunately, the rapid appearance of symptoms offers more of a chance for quick detection. Both trypanosomes are transferred to the tsetse fly when the fly obtains a blood meal from an infected person. The trypanosomes then multiply in the blood of the fly, and can be transferred to a susceptible person on whom the fly subsequently feeds. The early symptoms of the disease include fever, severe headache, joint pain, and swelling of the lymph nodes. These symptoms can disappear and reoccur. Later, symptoms of what is called the neurological phase emerge and often include the characteristic symptoms of the disease: extreme weakness, paralysis of eye muscles, sleepiness, disruption of the sleep cycle, and a lapse into a deep and fatal coma. Transmission of the trypanosomes across the placenta from a pregnant woman to the fetus can occur. Typically this causes spontaneous abortion or death of the fetus.

Diagnosis The most useful diagnostic sign is swollen cervical glands. This indicates the presence of the parasite. Populations can be screened for clinical signs of the disease (the

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Encephalitis Inflammation of the brain, usually caused by a virus. The inflammation may interfere with normal brain function and may cause seizures, sleepiness, confusion, personality changes, weakness in one or more parts of the body, and even coma. Parasite An organism that lives and feeds in or on another organism (the host) and does nothing to benefit the host. Vector-borne disease A disease that is delivered from one host to another by a vector or carrier organism.

early phase symptoms) and the use of tests that detect antibodies to the parasite in the blood. An early diagnostic sign of the bite of the tsetse fly is the appearance of a painful red sore (chancre) at the site of the bite. A type of diagnosis called phase diagnosis can be used to help determine the level of advancement of the disease. Cerebro-spinal fluid is obtained by the technique of lumbar puncture and analyzed. Phase diagnosis requires medical and laboratory staff, and is typically done in a clinic. The long period, symptom-free period of a Trypanosoma brucei gambiense infection can complicate and delay diagnosis.

Treatment team Physicians and nurses are the primary team involved in treating encephalitis lethargica. Additionally, public health workers in Africa and other areas affected with the tsetse fly receive help from health agencies throughout the world, who provide aid and strategies to reduce populations of the fly, educate local peoples to bite prevention methods, and treat affected individuals. Warring factions, with resulting political instability and hunger in the SubSaharan region of Africa have led to difficulty in controlling the spread of the tsetse fly and the disease.

Treatment The choice of treatment depends on whether the disease is detected earlier or later in the infection. Early-stage infections can be treated using two drugs; suramine and pentamidine. An agreement between the World Health Organization and the drug’s manufacturer (Aventis) has guaranteed continued production of the compounds.

Recovery and rehabilitation Recovery from the early stage of the disease can be complete. Recovery from the neurological stage is typically incomplete, with varying degrees of impaired brain function often resulting. Once the person reaches the stage of coma, the disease is invariably fatal.

Clinical trials As of early 2004, there were no clinical trials in progress for the study of encephalitis lethargica. Rather, efforts to increase screening of susceptible populations and to increase the supply of drugs is the identified priority for scientists working with the disease.

Prognosis If treated early, a person with encephalitis lethargica can be cured. If not treated early, the prognosis is much less favorable due to resulting brain damage. Encephalitis lethargica is fatal if untreated. Resources BOOKS

Dumas, Michel, et. al. Progress in Human African Trypanosomiasis, Sleeping Sickness. New York: Springer Verlag, 1999. Ramen, Fred. Sleeping Sickness and Other Parasitic Tropical Diseases (Epidemics). New York: Rosen Publishing Group, 2002. OTHER

African Trypanosomiasis or Sleeping Sickness. World Health Organization. (January 27 2004). East African Trypanosomiasis. Centers for Disease Control and Prevention. (January 27 2004). ORGANIZATIONS

Centers for Disease Control and Prevention (CDC). 1600 Clifton Road, Atlanta, GA 30333. (404) 639-3311 or (800) 311-3435. .

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Key Terms

Treatment of the later, neurological symptoms requires a drug that can cross the blood-brain barrier to reach the parasite. Currently only one drug (melarsoprol) is commercially available. The drug causes harsh side effects and itself has a fatal complication rate approaching 10%. As well, resistance of the trypanosomes to the drug is increasing. A second drug (eflornithine) exists, but is not commercially available. It is active only against Trypanosoma brucei gambiense. There is no vaccine for the disease.

Encephaloceles

World Health Organization (WHO). Avenue Appia 20, 1211 Geneva, Geneva, Switzerland. +41 22 791 21 11; Fax: +41 22 791-3111. [email protected]. .

Brian Douglas Hoyle, PhD

Cerebrospinal fluid A clear fluid that is produced in the ventricles of the brain and circulates around and within the brain and spinal cord. Neural tube defect A birth defect caused by abnormal closure or development of the neural tube, the embryonic structure that gives rise to the central nervous system.

❙ Encephaloceles Definition

Encephaloceles refers to defects in the development of a fetal structure called the neural tube. The tube fails to close completely during development of the fetus, resulting in portions of the brain and its surrounding membranes that protrude from the skull in sac-like formations. Often, normal brain function is impaired and children with encephaloceles experience delays in development.

Description In normal fetal development, the neural tube forms by the closure of the neural structure. When this does not occur in the case of an encephalocele, the result is a groove. The groove can form down the middle region of the upper part of the skull, or between the forehead and the nose, or down the back of the skull. The incomplete closure also creates areas where the brain and its overlaying membrane can bulge outward in sac-like protrusions. The larger deformities, in particular those that occur at the back of the skull, are readily evident and are recognized very soon after birth. These deformities are also associated with abnormal structure and functioning of the brain. Some encephaloceles are less evident, even to the point of being undetectable at birth. Defects in the region of the forehead and nose are examples.

Demographics Encephaloceles occur rarely. At a rate of one per 5,000–10,000 live births, an encephalocele is less common than spina bifida, another neural tube defect. Geographical differences occur with respect to the type of encephalocele. Malformation of the back portion of the head is more common in Europe and North America, whereas involvement of the front portion of the head occurs more frequently in Southeast Asia, Malaysia, and Russia.

Teratogen A substance that has been demonstrated to cause physical defects in the developing human embryo.

of spina bifida. It is clear that one or more genetic abnormalities lie at the heart of the condition. However, fetal development is an extremely complex process, with interactions between various genes, and influence of the external environment determining which genes are activated at which time. Thus, pinning down the crucial genes whose expression or changed activity produces abnormal neural tube formation is a difficult task. Research using animal models has shown that teratogens, compounds like x rays, trypan blue, and arsenic, which can damage the developing fetus, cause encephaloceles in the animals. Whether exposure of a human fetus to such agents contributes to encephalocele formation in humans is not known. Most often, the symptoms of encephaloceles are not difficult to recognize. These include the excessive build-up of cerebrospinal fluid in the brain (a condition called hydrocephalus), paralyzed arms and legs (spastic quadriplegia), an abnormally small head (microcephaly), difficulty in tasks like walking and reaching because of a lack of coordination (ataxia), delayed or impaired mental and physical development (although intelligence is not always affected), problems with vision, and seizures. If the bulging portion contains only cerebrospinal fluid and the overlaying membrane, the malady can also be called a cranial meningocele or a meningocele. If brain tissue is also present, the malady can also be referred to as an encephalomeningocele.

Diagnosis

Causes and symptoms The exact cause of encephaloceles is not yet known. The disorder is passed on from generation to generation, and is more prevalent in families where there is a history

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Key Terms

Diagnosis is based at the discovery of the physical abnormalities at birth or sometime later, and on the failure to attain the various physical and mental developmental milestones that are a normal part of early life.

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Encephaloceles

Encephalocele, a brain formation growing outside the skull, on a 16-week-old fetus. (© Siebert/Custom Medical Stock Photo. Reproduced by permission.)

Treatment team Medical treatment involves family physicians, neurosurgeons, and nurses. Special education professionals, physical therapists, and caregivers are also an important part of the treatment team, as an affected person may require assistance in everyday activities throughout life.

Treatment Treatment typically involves surgery. The surgery is usually accomplished soon after birth, and re-positions the bulging brain back into the skull, removes any of the saclike protrusions, and corrects the skull deformities. Often, shunts are placed during surgery to drain excess cerebrospinal fluid from the brain. While delicate, the operation typically relieves the pressure that would otherwise impede normal brain development. Other treatment

involves dealing with specific symptoms and producing as comfortable and satisfying everyday life as is possible.

Recovery and rehabilitation Prospects for recovery are difficult to predict prior to surgery. Nonetheless, if surgery is successful, and other developmental difficulties have not occurred, an individual can develop normally. Where neurological and developmental damage has occurred, the focus shifts from recovery to maximizing mental and physical abilities.

Clinical trials As of April 2004, no clinical trails for specific study of encephaloceles were being conducted. However, research is underway to more clearly define the mechanisms of brain development, and several clinical trials related to

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Encephalopathy

neural tube defects are recruiting participants. Updated information can be found at the National Institutes of Health clinical trials website at: http://clinicaltrials.gov.

Prognosis As for recovery and rehabilitation, the prognosis is varies and cannot be predicted beforehand. In general, when the bulging material consists of mainly cerebrospinal fluid, a complete recovery can occur 60–80% of the time. However, the presence of brain tissue in the protruding material can reduce the chances of a complete recovery considerably.

Special concerns Folic acid, a B vitamin, has been shown to help prevent neural tube defects when taken before and in early pregnancy. The March of Dimes organization and the United States Public Health Service recommend that all women who may become pregnant take a multi-vitamin that contains 400 micrograms of folic acid every day. Resources BOOKS

McComb, G. G., ed. Neural Tube Defects. American Association of Neurological Surgeons, 1998. PERIODICALS

“Beaumont surgeons correct rare defect for Caribbean boy.” Health Week (July 1, 2002): 17. OTHER

NINDS Encephaloceles Information Page. National Institute of Neurological Disorders and Stroke. (April 7, 2004).

Prevention of Neural Tube Defects. The Arc. (April 10, 2004).

ORGANIZATIONS

Birth Defect Research for Children. 930 Woodcock Road, Suite 225. Orlando, FL 22808. (407) 895-0802 or (800) 313-2232; Fax: (407) 895-0824. March of Dimes Birth Defects Foundation. 1275 Mamaroneck Avenue, White Plains, NY 10605. (914) 428-7100 or (888) 663-4637; Fax: (914) 428-8203. askus@ marchofdimes.com. . National Institute for Neurological Diseases and Stroke (NINDS). 6001 Executive Boulevard, Bethesda, MD, 20892. (301) 496-5751 or (800) 352-9424. . National Organization for Rare Disorders. 55 Kenosia Avenue, Danbury, CT 06813-1968. (203) 744-0100 or (800) 9996673; Fax: (203) 798-2291. [email protected]. .

Brian Douglas Hoyle, PhD

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❙ Encephalopathy Definition

Encephalopathy is a condition characterized by altered brain function and structure. It is caused by diffuse brain disease.

Description Encephalopathy may be caused by advanced and severe disease states, infections, or as a result of taking certain medications. The three main causes of encephalopathy are liver disease, kidney disease, and lack of oxygen in the brain. The associated symptoms can include subtle personality changes, inability to concentrate, lethargy, progressive loss of memory and thinking abilities, progressive loss of consciousness, and abnormal involuntary movements. Symptoms vary with the severity and type of encephalopathy. Encephalopathy may vary in severity from only subtle changes in mental state to a more advanced state that can lead to deep coma. Cerebral edema is a common manifestation of severe encephalopathy, which causes an increase in intracranial pressure. The major related causes of death include sepsis, circulatory collapse, and brain failure related to a syndrome encompassing cerebral edema, damaged blood-brain-barrier, increased intracranial pressure, brainstem herniation, and/or neurotoxins leaking into the brain and killing brain cells. Additionally, patients with severe encephalopathy usually develop intracranial hypertension, which can produce cerebral ischemia injury and cerebral herniation.

Demographics There is no statistical information available for encephalopathy per se. Encephalopathy can occur at any age and there seems to be no gender or racial predilection, because encephalopathy is a manifestation of a primary illness.

Causes and symptoms Causes There is a wide variety of conditions that cause encephalopathy. Encephalopathy can be caused by infections (bacteria, viruses, or prions); lack of oxygen to the brain; liver failure; kidney failure; alcohol/drug overdose; prolonged exposure to toxic chemical (solvents, paints, industrial chemicals, drugs, radiation); metabolic diseases; brain tumor; increased intracranial pressure; and poor nutrition. HYPOXIC ENCEPHALOPATHY Hypoxic encephalopathy refers to a lack of oxygen to the entire brain, which

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Cerebral herniation against the skull.

Movement of the brain

Cerebral ischemia Lack of oxygen to the brain, which may result in tissue death. Encephalogram Machine that detects brain activity by measuring electrical activity in the brain. Intracranial hypertension Increase in pressure in the brain.

typically results in brain damage. Cerebral hypoxia can be caused by drowning, low blood pressure, birth injuries, cardiac arrest, strangulation, asphyxiation caused by smoke inhalation, severe hemorrhage, carbon monoxide poisoning, high altitudes, choking, tracheal compression, complications of anesthesia, paralysis of respiratory muscles, and respiratory failure. Cardiac arrest is the most common condition that causes cerebral hypoxia. When the heart stops pumping, oxygen-rich blood cannot be delivered to vital organs such as the brain. Hypoxia to the brain causes irreversible brain damage after two minutes. HEPATIC ENCEPHALOPATHY Hepatic encephalopathy refers to a condition of brain and nervous system damage caused by liver (hepatic) failure. Diseases that damage the liver causing impairment of the detoxification and functional capabilities of the liver can cause hepatic encephalopathy. Examples of disorders that decrease liver function are hepatitis or cirrhosis. Impairment in the detoxification capabilities of the liver causes accumulation of toxic chemicals in the blood such as ammonia, in addition to many other impurities that all collectively cause damage to the nervous system. KIDNEY FAILURE The main function for the kidneys is to eliminate excess fluid and waste material from the blood. When the kidneys lose the ability to filter the blood, dangerous levels of waste products accumulate in the body. Chronic renal failure can be caused by diabetes, analgesic nephropathy (due to long-term use of aspirin or nonsteroidal anti-inflammatory drugs), kidney diseases (polycystic kidney disease, pyelonephritis, and glomerulonephritis), renal artery stenosis (a narrowing of the artery that supplies blood to the kidneys), and lead poisoning. SEVERE INFECTIONS Severe infections, especially those that affect the brain, can cause encephalopathy. Infections that specifically target the brain are encephalitis, which is inflammation of the brain, typically caused by a

CHRONIC ALCOHOL USE Long-term use of alcohol not only causes destruction of brain cells but can cause cirrhosis of the liver or hepatitis, which results in the destruction of liver cells. Chronic alcoholism leads to progressive destruction of liver cells, which can cause end-stage liver failure. A subtype of hepatitis infection called hepatitis C typically causes progressive destruction to liver cells. UREMIC ENCEPHALOPATHY Uremia describes the final stage of progressive renal insufficiency, which culminates in end-stage kidney failure with neurologic involvement. This is called uremic encephalopathy. The cause is unknown and no single metabolite or toxin is responsible for symptoms, but rather it is an accumulation of several chemicals/toxins in the blood that causes symptoms of encephalopathy.

Symptoms The hallmark of encephalopathy is altered mental state. In mild cases, hypoxia can cause an altered mental state, which includes symptoms such as motor incoordination, poor judgment, and inattentiveness. Mild cases have no lasting effects. Patients who have severe hypoxia or anoxia (total lack of oxygen delivery, usually from cardiac arrest) lose consciousness within seconds. Other symptoms of encephalopathy include lethargy, nystagmus (rapid, involuntary eye movement), tremor, dementia, seizures, myoclonus (involuntary twitching of a muscle or group of muscles), muscle weakness and atrophy, and loss of ability to speak or swallow. An early and characteristic feature of hepatic encephalopathy is called constitutional apraxia, which is inability to reproduce simple designs such as a star. Patients with liver failure may exhibit a symptom called asterixis, an involuntary jerking tremor of the hands.

Diagnosis The diagnosis of encephalopathy depends on the presence of acute or chronic liver disease; altered mental state such as confusion, stupor, or coma; symptoms of central nervous system damage; and abnormal wave patterns on an encephalogram. Diagnostic tests that may be utilized to establish the diagnosis include, but are not to limited to: complete blood count; liver function tests; ammonia and glucose levels; lactate levels (often elevated due to impaired tissue perfusion and because of decreased clearance by the liver); arterial blood gases (may reveal hypoxemia); kidney function tests; blood cultures (to detect infectious agents); virology testing (for hepatitis); neuroimaging studies; and ultrasound studies.

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Encephalopathy

Key Terms

virus, or meningitis, which is inflammation of the tissue that surrounds and protects the brain.

Encephalopathy

Treatment team The causes of encephalopathies are broad. Additionally, the symptoms are also broad, ranging from mild changes of consciousness to coma or death. Therefore, the treatment team can consist of a broad spectrum of specialists that can include, but is not limited to, an internist, oncologist, pulmonologist, critical care physician, radiologist, hepatologist (specialist in liver diseases), and surgeon. The disorder can also occur in the pediatric ages or even at birth. In these critical situations, specialists in pediatric critical care, a neonatologist, and a perinatologist (specialist in maternal-fetal health) would be involved.

Prognosis The outcome for patients who present with symptoms of encephalopathy depends on the cause. If the cause can be corrected in time, the outcome can be favorable. However, if encephalopathy is a manifestation of more advanced chronic disease, or if it is part of a rapidly fulminating disorder, the outcome can be poor and death may ensue due to the primary cause.

Special concerns

Treatment Hypoxia or anoxic encephalopathy is an emergency, and immediate measures are necessary to prevent further damage to the brain and to restore breathing and circulation. It is necessary to treat hepatic encephalopathy early to prevent long-term damage. Specific treatment for hepatic encephalopathy is aimed at eliminating toxic substances and/or treatment of the primary illness that caused encephalopathy. Elimination of toxins such as ammonia can be accomplished by decreasing absorption of protein from the gut. By giving the patient a compound called lactulose, absorption of ammonia can be decreased. Persons with hepatic encephalopathy should not consume protein, and constipation should be avoided. Uremic encephalopathy caused by chronic renal failure is treated with transplantation or dialysis.

Recovery and rehabilitation Recovery is an emergency for all patients with severe hypoxia or anoxia. Vital functions such as breathing, cardiac function, and delivery of oxygen-rich blood to the brain should be restored within two to five minutes. If anoxia persists for more than two minutes, there will be permanent and severe damage to the brain.

Clinical trials There are four active government-sponsored clinical trials that are recruiting patients. There is a phase III clinical trial concerning birth asphyxia (hypoxic-ischemic encephalopathy) in infants up to six hours old. A phase II clinical trial is investigating the neuroimaging findings associated with persistent encephalopathy caused by the ticktransmitted infection called Lyme’s disease (persistent Lyme encephalopathy). A third study is investigating a genetic form of familial dementia that causes encephaolpathy due to neurodegeneration of brain tissue. A fourth study investigates a disorder called neuronal ceroid lipofuscinosis (NCLS), which is a common heritable form of encephaopathy that occurs in one of 12,500 children. Detailed 344

information about each of these studies can be obtained online from the website .

Persons who present with encephalopathy have advanced disease or the beginning of an advanced disease process. Vigilance on the part of the primary care provider is necessary to take all precautions to prevent this process. Resources BOOKS

Goetz, Christopher G., et al. (eds). Textbook of Clinical Neurology, 1st ed. Philadelphia: W.B. Saunders Company, 1999. Goldman, Lee, et al. Cecil’s Textbook of Medicine, 21st ed. Philadelphia: WB. Saunders Company, 2000. Noble, John, et al. (eds). Textbook of Primary Care Medicine, 3rd ed. St. Louis: Mosby, Inc., 2001. Rakel, Robert A. Textbook of Family Practice, 6th ed. Philadelphia: WB Saunders Company, 2002. Rosen, Peter. Emergency Medicine: Concepts and Clinical Practice, 4th ed. St Louis: Mosby Year Book, Inc., 1998. PERIODICALS

“Encephalopathy.” eMedicine Series (July 2001). Saas, David A. “Fulminant Hepatic Failure.” Gastroenterology Clinics 32:4 (December 2003). WEBSITES

NINDS Encephalopathy Information Page. National Institute of Neurological Disorders and Stroke. (May 20, 2004). . ORGANIZATIONS

National Institute of Neurological Disorders and Stroke NIH Neurological Institute. P.O. Box 5801, Bethesda, MD 20824. (301) 496-5751 or (800) 352-9424. .

Laith Farid Gulli, MD Alfredo Mori, MB, BS

Encephalotrigeminal angiomatosis see Sturge-Weber syndrome

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Definition

Endovascular embolization is a procedure that utilizes chemical agents or metallic coils to stop bleeding and treat aneurysms or brain tumors.

Purpose The purpose is either to cut off blood supply or to fill a sac (also creating a thrombus). Endovascular embolization is a procedure used to treat hemorrhage, cranial tumors, or aneurysms. The procedure can be life saving. Bleeding can be stopped in cases of trauma, epistaxis (nosebleed), coughing up blood from the lungs (hemoptysis), gastrointestinal bleeding, hemorrhage to solid organs, and postcesarean, postoperative, or postpartum bleeding in the abdomen or pelvis. Additionally, endovascular embolization is used to cut off the blood supply to cranial tumors which eventually causes tumor cell destruction and tumor mass shrinkage from lack of oxygen and nourishment. The procedure can also be utilized for packing an aneurysm with coils, to prevent rupture and possible death from intracranial hemorrhage.

Precautions Embolization is an indication for treatment of many clinical entities. The procedure is performed under general anesthesia and elective cases require pre-procedural evaluation with an anesthesiologist. The procedure requires a brief inpatient stay for one to two days. Dietary restrictions and medical work-up are usually indicated before elective surgery (i.e., cranial tumors). If an aneurysm or tumor cannot be safely embolized, the procedure is terminated. For bleeding, the procedure may likely be an emergency.

Description Embolization is a useful procedure in a broad spectrum of clinical disorders. Typically embolization for any reason begins with a diagnostic angiography procedure to identify the source of the problem. The diagnostic angiography is usually performed in an artery. A catheter is usually inserted into the groin artery and dye is injected into the system. The catheter is wiggled through to the desired location using a television monitor. The target area may be a region where there is bleeding or it may be an aneurysm or cranial tumor. Once at the target area, chemicals or metal coils (for an aneurysm) are introduced by a microcatheter. In the case of an aneurysm, soft metal coils are placed with a microcatheter in the aneurysm until it is packed with about five to six coils. Filling the aneurysm will prevent blood flow into the aneurysm sac, since the

Preparation Routine blood tests are done one to two days before an elective embolization. For scheduled procedures the patient should not eat or drink liquids after midnight the night before the procedure. The procedure is usually performed in a neuroangiography unit. A nurse will shave the patient’s groin area since the catheter is inserted in the groin artery (also called the femoral artery). Emergency preparation may be initiated for persons who are actively bleeding.

Aftercare After elective embolization, patients are taken to a neurosurgical intensive care unit or a step-down unit for close monitoring and recovery. It is necessary to lie flat for eight hours after the procedure to allow the groin area (where the catheter was inserted) to heal. Usually the next day the patient will be transferred to a regular ward room and discharged to home the following day.

Risks The risk of embolization is low. Possible complications include weakness in an arm or leg, dysesthesia, speech or visual deficits, and stroke.

Normal results Normal results depend on the indications for the procedure. For bleeding the desired goal is rapid cessation of bleeding source. Aneurysm will likely develop saccular occlusion (occlusion of the aneurysm sac), reducing the risk of rupture and fatal intracranial hemorrhage. The desired effect for an intracranial tumor is obliteration of tumor vasculature, which eventually causes destruction of the tumor mass, secondary to oxygen deprivation. Resources BOOKS

Grainger, Ronald G., and David Allison. Grainger & Allison’s Diagnostic Radiology: A Textbook of Medical Imaging, 4th Ed. Churchill Livingstone, Inc. WEBSITES

Arteriovenous Malformations. The Mayfield Clinic. .

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Endovascular embolization

❙ Endovascular embolization

sac is filled with coils and a thrombus after the procedure. Endovascular embolization can help to stop bleeding or rebleeding for patients who are hemorrhaging. For cranial tumors the goal is to inject emboli in blood vessels that nourish brain tumors. This causes destruction of the tumor mass due to lack of blood supply. For any reason, when a blood vessel requires embolization, coils are the instrument of choice.

Epidural hematoma

Key Terms Aneurysm A sac formed by dilatation of an arterial wall. Dysesthesia tingling.

Painful feeling of numbness and

Endovascular Embolization of Cranial Tumors. University of North Carolina at Chapel Hill. . Endovascular Embolization Treatment of Aneurysms. The University of Toronto. . ORGANIZATIONS

International Radiosurgery Support Association. PO Box 5186, Harrisburg, PA 17110. (717) 260-9808; Fax: (717) 2609809. [email protected]. .

Laith Farid Gulli, MD Robert Ramirez, DO

❙ Epidural hematoma

Demographics Traumatic brain injuries such as those that can result in cranial epidural hematoma are common. About 500,000 patients are admitted to hospitals in the United States annually with head injuries that cause brain damage, and some 75,000–90,000 of these patients die. Motor vehicle accidents are the most common cause of closedhead injuries, accounting for 50–70% of such injuries. Falls are the second most common cause of closed head trauma. Alcohol is a contributing factor in about 40% of severe head injuries. Sports such as football can result in traumatic head injury, but do so relatively rarely. Threequarters of patients with traumatic brain injury are male, and the risk of traumatic brain injury declines steadily with age. Epidural hematoma occurs in about 1% of all patients with severe head injuries. The fraction of comatose headinjury patients with subdural hematoma is greater, but still only about 10%.

Causes and symptoms

Definition

Intracranial subdural hematoma

An epidural hematoma is a pocket of blood that forms immediately outside the dura mater. The dura mater is the fibrous outermost sheath or membrane that encloses the brain and spinal cord. Epidural means outside the dura, and hematoma means mass of blood.

Description Epidural hematomas usually form when a violent blow breaks a blood vessel in the space outside the dura mater, whether in the skull or in the spinal column. In the skull, the vessel most often responsible for epidural hematoma is the middle meningeal artery. Blood from the broken vessel forms a pressurized pocket of blood, like a large, internal blood blister. The growing hematoma pushes against the rigid bone of the skull or spinal column and thus exerts pressure on the dura mater, which in turn pushes on the brain or spinal cord. This pressure may stretch and tear blood vessels or even force the brain to herniate (i.e., partially squeeze out) through the foramen magnum, the hole in the bottom of the skull through which the spinal cord enters, or through the tentorium cerebelli, the part of the dura mater that covers the cerebellum and supports the occipital lobes from below. Herniation of the brain is likely to be fatal. 346

Epidural hematomas are less common than subdural hematomas, which are the most common mechanism of fatal brain damage in head trauma. They are also distinguished from intracranial hematomas, volumes of blood that collect inside the brain rather than at its surface.

The most common cause of cranial epidural hematoma is head trauma, which is some kind of blow to the head. Epidural hematomas are most commonly found in the temporal or temporoparietal region, i.e., along the sides of the brain. Patients often lose consciousness due to the original head trauma, regain consciousness and undergo a period of clear-mindedness, then deteriorate neurologically. Spinal epidural hematoma Trauma is a common cause of spinal epidural hematoma. Non-trauma causes include anticoagulant therapy, hemophilia, liver disease, aspirin use, systemic lupus erythematosus, and, rarely, lumbar puncture. In 40–50% of cases of spinal epidural hematoma, no precipitating trauma or other cause is observed; these cases are considered spontaneous. Spinal epidural hematoma causes compression of the spinal cord. Symptoms vary with the amount and location of this pressure. Back pain may be slight or absent. The patient may have loss of feeling (anesthesia) or less-thannormal feeling (hypoesthesia) in the legs, arm, or trunk. There may be weakening of the legs and loss of deep tendon reflexes. There may be bowel and bladder dysfunction

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Dura mater The tough, fibrous outermost layer of the three meninges that surround the brain and spinal cord. Hematoma A bruise or collection of blood within soft tissue that results in swelling.

Treatment Emergency care for spinal trauma consists of immobilizing the patient and administering high-dose corticosteroids. However, the highest priority for any intracranial or spinal hematoma is relief of the pressure by surgical drainage of the hematoma.

(e.g., incontinence or inability to control the bladder or bowels).

Diagnosis Neurologic assessment is the first step in determining the severity of a head injury. The patient’s speech, eyeopening, and muscular responses are evaluated, along with the orientation (if conscious) to place, time, and commands to open eyes or the like. If the patient is unconscious, examination of the pupillary light reflex is important. An epidural or other hematoma increases intracranial pressure, which quickly has an effect on the third cranial nerve, which contains, among other nerve fibers, those that control constriction of the pupil. Pressure that blocks this nerve leads to fixed dilation of the pupil. Fixed pupil dilation in one or both eyes is a strong indicator that the patient may have an intracranial hematoma. To distinguish between epidural, subdural, and intracranial hematoma, computerized tomography (CT) or magnetic resonance imaging (MRI) is probably necessary. Surgeons determine if swelling on one side of the brain has shifted the midline of the brain. If a shift of more than 0.2 in (5 mm) is found, an emergency craniotomy (opening of the skull) may be performed. Patients with spinal epidural hematoma may experience sudden onset of back or neck pain at the site of the bleed. Coughing or any other maneuver that increases pressure inside the torso may worsen the pain transiently. In children, the bleeding is more likely to be in the cervical (neck) region than in the thoracic (middle back) region.

Recovery and rehabilitation Epidural hematoma can result in permanent paralysis or other neurological deficits. If spinal cord compression due to hematoma is alleviated within 6–12 hours, permanent symptoms may be avoided. Prevention of brain damage depends more on preventing the brain from being deformed by the pressure of the hematoma than on relieving that pressure. Rehabilitation needs will depend on how much permanent damage, if any, has been caused.

Clinical trials As of 2004, no clinical trials were being conducted for epidural hematoma patients in the United States. Resources PERIODICALS

Marsh, Cherly. “Surgical Management of Patients with Severe Head Injuries.” AORN Journal May 1, 1996. Sung, Helen Minjung. “How to Diagnose and Treat Acute, Nontraumatic Spinal Cord Lesions.” The Journal of Critical Illness April 1, 2000. Trask, Todd. “Management of Head Trauma (Critical Care Review).” Chest August 1, 2002. OTHER

Epidural Hematoma Patient/Family Resources. April 26, 2004 (May 30, 2004). . NINDS Traumatic Brain Injury Information Page. National Institute of Neurological Disorders and Stroke. April 26, 2004 (May 30, 2004). .

When making the diagnosis of spinal epidural hematoma, physicians must decide whether the symptoms of spinal compression are being caused by a hematoma or by a tumor. CT or MRI are definitive in distinguishing between compression of the spinal cord caused by tumor or hematoma.

Treatment team Treatment for hematoma is primarily surgical. A neurologist and a neurosurgeon will be essential members of

Larry Gilman

❙ Epilepsy Definition

The words “epilepsy” and “epileptic” are of Greek origin and have the same root as the verb “epilambanein,” which means “to seize” or “to attack.” Therefore, epilepsy

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Epidural hematoma

Key Terms

the treatment team, as will nursing staff, in the operating room and out of it, who are specially trained in head trauma care.

Epilepsy

means seizure, while epileptic means seized. In the modern understanding of epilepsy, it should not be considered a disease. Rather, it is a symptom indicating a medical condition in the brain that causes a potential for recurrent seizures. The condition of epilepsy has many causes and the kinds of seizures that occur can vary widely.

Description The word epilepsy is actually a descriptive term. It takes into account an individual’s risk of recurrent seizures. However, when people are suffering from meningitis and have a seizure, they would not be considered to have epilepsy unless they had a seizure after the meningitis resolved. In this case, these individuals have a risk for recurrent seizures and, hence, epilepsy. If an individual over time does not have any seizures off medications, then it could be said that epilepsy has resolved or gone into remission. For thousands of years, epilepsy was looked upon differently than most other medical problems. Because of this, epilepsy has been fraught with social stigmas, even up to today. The ancient Greeks knew about the condition that led to a sudden attack upon the unfortunate. Although Hippocrates, in roughly 400 B.C., referred to epilepsy as the sacred disease, he did so to emphasize the general public’s superstitious view of the condition. Of course, it certainly was not an affliction sent from a deity, nor was it even a demon. Nevertheless, seizures, which manifest in unusual behaviors, mystified observers who considered this illness, from all others, as coming from another world. The current understanding of epilepsy is a recent development. Previously, it was not even believed that the brain had electrical properties. It was not until the last few centuries that the brain was considered the seat of the mind; it was the heart or the lungs that were commonly regarded as the organ of thought. Physicians struggled with what to even call a seizure. In general, any behavior that resulted in a loss of consciousness or convulsions was labeled a seizure. It is likely that episodes of fainting were erroneously called seizures. Finally, in 1873, an adequate definition for the term seizure finally came into existence. The famous English neurologist John Hughlings Jackson explained epilepsy as “a sudden, excessive, and rapid discharge of gray matter of some part of the brain” that would correspond to the patient’s experience.

Automatisms Movements during a seizure that are semi-purposeful but involuntary. Gelastic seizures Seizures manifesting with brief involuntary laughter. Gray matter The portion of the brain that contains neurons, as opposed to white matter, which contains nerve tracts. Spike wave discharge Characteristic abnormal wave pattern in the electroencephalogram that is a hallmark of an area that has the potential of generating a seizure.

all combined. The risk of experiencing one seizure in the course of a lifetime, from any cause, is close to 10%. However, there is an approximately 1% chance of developing epilepsy in the general population before the age of 20. The risk increases to 3% by age 75. Of course, depending on the age group being studied, the cause of epilepsy will vary. The incidence of epilepsy is relatively constant among different ethnic groups and similar between genders. However, there may be variation in incidence in underdeveloped countries due to access to care and endemic illness that can cause seizures, such as neurocystercercosis in Latin American countries.

Causes and symptoms Epilepsy has many causes that, in part, have an affect on the clinical presentation of symptoms. In order for epilepsy to occur, there must be an underlying physical problem in the brain. The problem can be so mild that an individual is perfectly normal other than seizures. The brain has roughly 50–100 billion neurons. Each neuron can have up to 10,000 contacts with neighboring neurons. Hence, trillions of connections exist. However, only a very small area of dysfunctional brain tissue is necessary to create a persistent generator of seizures and, hence, epilepsy. The following are potential causes of epilepsy: • genetic and/or hereditary • perinatal neurological insults • trauma with brain injury • stroke

Demographics More than 2.5 million Americans suffer from epilepsy, and more than another 50 million worldwide. Epilepsy is more common than Parkinson’s disease, multiple sclerosis, cerebral palsy, and muscular dystrophy 348

Key Terms

• brain tumors • infections such as meningitis and encephalitis • multiple sclerosis • ideopathic (unknown or genetic)

GALE ENCYCLOPEDIA OF NEUROLOGICAL DISORDERS

• Ohtahara syndrome • migrating partial seizures of infancy (syndrome in development) • West syndrome • benign myoclonic epilepsy in infancy • benign familial and non-familial infantile seizures • Dravet’s syndrome • HH syndrome • myoclonic status in nonprogressive encephalopathies (syndrome in development) • benign childhood epilepsy with centrotemporal spikes • early onset benign childhood occipital epilepsy (Panayiotopoulos type) • late-onset childhood occipital epilepsy (Gastaut type) • epilepsy with myoclonic absences • epilepsy with myoclonic-astatic seizures • Lennox-Gastaut syndrome • Landau-Kleffner syndrome (LKS) • epilepsy with continuous spike-and-waves during slowwave sleep (other than LKS) • childhood absence epilepsy • progressive myoclonus epilepsies • idiopathic generalized epilepsies with variable phenotypes include juvenile absence epilepsy, juvenile myoclonic epilepsy, and epilepsy with generalized tonic-clonic seizures only • reflex epilepsies • idiopathic photosensitive occipital lobe epilepsy • other visual sensitive epilepsies • primary reading epilepsy • startle epilepsy • autosomal dominant nocturnal frontal lobe epilepsy • familial temporal lobe epilepsies • generalized epilepsies with febrile seizures plus (syndrome in development) • familial focal epilepsy with variable foci (syndrome in development) • symptomatic focal epilepsies • limbic epilepsies • mesial temporal lobe epilepsy with hippocampal sclerosis • mesial temporal lobe epilepsy defined by specific etiologies • neocortical epilepsies • Rasmussen syndrome Classifying epilepsy can help in the evaluation and management of patients with seizure disorders. The combination of seizure type(s), etiology (cause), age of onset,

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Epilepsy

Any of the above conditions have the potential for causing the brain or a portion of it to be dysfunctional and produce recurrent seizures. Regardless of the exact cause, epilepsy is a paroxysmal (sudden) condition. It involves the synchronous discharging of a population of neurons. This is an abnormal event that, depending on the location in the brain, will correspond to the particular symptoms of a seizure. The International League Against Epilepsy (ILAE) issued a classification of types of seizures. The list gives the kind of seizures that can occur. Individual seizure types are based on the clinical behavior (semiology) and electrophysiological characteristics as seen on an electroencephalogram (EEG). Generalized seizures included in the list are: • tonic-clonic seizures (includes variations beginning with a clonic or myoclonic phase) • clonic seizures, including without tonic features and with tonic features • typical absence seizures • atypical absence seizures • myoclonic absence seizures • tonic seizures • spasms • myoclonic seizures • eyelid myoclonia, including without absences and with absences • myoclonic atonic seizures • negative myoclonus • atonic seizures • reflex seizures in generalized epilepsy syndromes Focal seizures included in the ILAE list are: • focal sensory seizures with elementary sensory symptoms (e.g., occipital and parietal lobe seizures) and experiential sensory symptoms (e.g., temporo-parietooccipital junction seizures) • focal motor seizures with elementary clonic motor signs, asymmetrical tonic motor seizures (e.g., supplementary motor seizures), typical (temporal lobe) automatisms (e.g., mesial temporal lobe seizures), hyperkinetic automatisms, focal negative myoclonus, and inhibitory motor seizures • gelastic seizures • hemiclonic seizures • secondarily generalized seizures • reflex seizures in focal epilepsy syndromes In 1989, the International League Against Epilepsy also issued the following classification of epilepsies and epileptic syndromes: • benign familial neonatal seizures • early myoclonic encephalopathy

Epilepsy PET scans of a human brain during the stages of an epileptic seizure; the middle image represents the most severe period of the seizure. (© Photo Researchers, Inc. Reproduced by permission.)

family history, and other medical or neurological conditions can be used to identify an epilepsy syndrome. Classification helps clinicians and researchers understand the broader picture of seizure disorders. On a practical level, syndrome identification can help in planning the management of patients. Syndrome classification schemes are revised periodically as individual components of particular categories are better understood. The term idiopathic refers to a cause that is suspected to be, if not genetic, then unknown. Cryptogenic is a term that suggests that an underlying cause is suspected, but not yet fully understood. Symptomatic is a term that is applied to epilepsies that are a result of understood underlying pathologies. The management and prognosis vary considerably among these differing syndromes. Epilepsies that have a genetic basis can be inherited or occur spontaneously. A 350

detailed family history can often identify other family members who have had seizures. However, because seizures are common, it is possible to have more than one family member with epilepsy, though the etiologies may not be related. To say that a particular type of epilepsy is genetic does not mean that it is necessarily transmitted by heredity. Often, disorders can have a genetic cause, but be spontaneously occurring in only one member of a family. In this case, there may simply be a random mutation in that particular person’s genes. There are several mechanisms in which epilepsies can be inherited. So-called simple Mendelian inheritance occurs with benign familial neonatal convulsions and autosomal dominant nocturnal frontal lobe epilepsy. On the other hand, complex inheritance mechanisms can involve more than one gene, or a gene mutation in combination with environmental or acquired factors such as juvenile

GALE ENCYCLOPEDIA OF NEUROLOGICAL DISORDERS

With epilepsy, symptoms vary considerably depending on the type. The common link among the epilepsies is, of course, seizures. The different epilepsies can sometimes be associated with more than one seizure type. This is the case with Lennox-Gastaut syndrome.

Diagnosis Arriving at a diagnosis of epilepsy is relatively straightforward: when people suffer two or more seizures, they would be considered to have epilepsy. However, diagnosing the specific epilepsy syndrome is much more complex. The first step in the evaluation process is to obtain a very detailed history of the illness, not only from the patient but from the family as well. Since seizures can impair consciousness, the patient may not be able to recall the specifics of the attacks. In these cases, family or friends that have witnessed the episodes can fill in the gaps about the particulars of the seizure. The description of the behaviors during a seizure can go a long way to categorizing the type of seizure and help with the overall diagnosis. Moreover, in the initial visit with the physician, the entire history of the patient is obtained. In a child, this would include birth history, complications, if any, maternal history, and developmental milestones. At any age, socalled co-morbidities (other medical problems) are considered. Medications that have been taken or currently being prescribed are documented. A complete physical examination is performed, especially a neurological exam. Because seizures are an episodic disorder, abnormal neurological findings may not be present. Frequently, people with epilepsy have a normal exam. However, in some, there can be abnormal findings that can provide clues to the underlying cause of epilepsy. For example, if someone has had a stroke that subsequently caused seizures, then the neurological exam can be expected to reveal a focal neurological deficit such as weakness or language difficulties. In some children with seizures, there can be a variety of associated neurologic abnormalities such as mental retardation and cerebral palsy that are themselves non-specific but indicate that the brain has suffered, at some point in development, an injury or malformation. Also, subtle findings on examination can lead to a diagnosis such as in tuberous sclerosis. This is an autosomal dominantly inherited disorder associated with infantile spasms in 25% of cases. On examination, patients have so-called ash-leaf spots and adenoma sebaceum on the skin. There can also be a variety of systemic abnormalities that involve the kidneys, retina, heart, and gums, depending on severity.

In the course of evaluating epilepsy, a number of tests are typically ordered. Usually, magnetic resonance image (MRI) of the brain is obtained. This is a scan that can help in finding many known causes of epilepsy such as tumors, strokes, trauma, and congenital malformations. However, while MRI can reveal incredible details of the brain, it cannot visualize the presence of abnormalities in the microscopic neuronal environment. Another test that is routinely ordered is an electroencephalogram (EEG). Unlike the MRI scan, this can be considered a functional test of the brain. The EEG measures the electrical activity of the brain. Some seizure disorders or epilepsies have a characteristic EEG with particular abnormalities that can help in diagnosis. Other tests that are frequently ordered are various blood tests that are also ordered in many medical conditions. These blood tests help to screen for abnormalities that can be a factor in the cause of seizures. Occasionally, genetic testing is performed in those instances where a known genetic cause is suspected and can be tested. A major concern in the course of an evaluation of epilepsy is to identify the presence of life-threatening causes such as brain tumors, infections, and cerebrovascular disease. Also, an accurate diagnosis can expedite the most effective treatment plan. The symptoms of epilepsy are dependent in part on the particular seizures that occur and other medical problems that may be associated. Seizures, themselves, can take on a variety of features. A simple sustained twitching of an extremity could be a focal seizure. If a seizure arises in the occipital lobes of the brains, then a visual experience can occur. Aura is a term often used to describe symptoms that a person may feel prior to the loss of consciousness of a seizure. However, auras are, themselves, small focal seizures that have not spread in the brain to involve consciousness. Smells, well-formed hallucinations, tingling sensations, or nausea have each occurred in auras. The particular sensation can be a clue as to the location in the brain where a seizure starts. Focal seizures can then spread to involve other areas of the brain and lead to an alteration of consciousness, and possibly convulsions. In certain epilepsy syndromes such as LennoxGastaut, there can be more than one type of seizure experienced, such as atonic, atypical absence, and tonicaxial seizures.

Treatment One challenge in predicting the course of epilepsy is that for any type, there can be a variable response to treatment. Sometimes, seizures may play a rather small role in the manifestation of a medical condition. For example, a severe head injury could result in seizures that readily respond to medication, but severe neurological impairments and disabilities may still be present. On the other hand, a

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myoclonic epilepsy. As the genetics of the epilepsies become better understood, the classification scheme will evolve.

Epilepsy

different head injury may result in relatively mild neurological problems, but there may be seizures that are severe and be resistant to medications. Whatever the case, the ultimate goals when treating epilepsy are to: • strive for complete freedom from seizures • be able to follow an easy regimen so that compliance with treatment can be maintained Up to 60% of patients with epilepsy can be expected to achieve control of seizures with medication(s). However, in the remaining 40%, epilepsy appears to be resistant, to varying degrees, to medications. In these cases, the epilepsy is termed medically intractable. Generally, the choice of medication is somewhat trial and error. There are, however, a number of considerations that guide the choice of treatment. Each medication has a particular side effect profile and mechanism of action. Some medications seem to be particularly effective for certain epilepsy syndromes. For example, juvenile myoclonic epilepsy responds well to valproic acid. On the other hand, ethosuxamide is primarily used for absence seizures. As with any medication, individuals can have very different experiences with same drug. Consequently, it is difficult to predict the efficacy of treatment in the beginning. A key concept of treatment is to first strive for monotherapy (or single drug therapy). This simplifies treatment and minimizes the chance of side effects. Sometimes, however, two or more drugs may be necessary to achieve satisfactory control of seizures. As with any treatment, potential side effects can be worse than the disease itself. Moreover, there is little point in controlling seizures if severe side effects limit quality of life. If a seizure disorder is characterized by mild, focal, or brief symptoms that do not interfere with day-to-day life, then aggressive treatments may not be justified. Epilepsy medications do not cure epilepsy; the medications can only control the frequency and severity of seizures. A list of the most commonly used medications in the management of epilepsy includes: • phenytoin (Dilantin, Phenytek) • clonazepam (Klonipin) • ethosuxamide (Zarontin) • carbamazepine (Tegretol, Carbatrol) • divalproex sodium (Depakote, Depakene) • felbamate (Felbatol) • gabapentin (Neurontin) 352

• topiramate (Topamax) • tiagabine (Gabatril) • zonisamide (Zonegran) • oxcarbazepine (Trileptal) • leviteracetam (Keppra)

• have little to no side effects from medications

• phenobarbital

• lamotrigine (Lamictal)

It has been found that the initial, thoughtfully chosen medication can be expected to make almost 50% of patients seizure free for extended periods of time. If the initial drug fails, another well-chosen drug may make an additional 14% of people seizure free. If that drug fails, then the likelihood of rendering someone with epilepsy seizure free is poor. This does not mean that trying more medications or combinations of them may not be successful, but rather, these statistics give the neurologist and the patient an understanding of the realities of epilepsy treatment. In cases where medications do not fully control epilepsy, it is recommended that a more extensive evaluation at a comprehensive epilepsy center be conducted where an epileptologist (a specialist in epilepsy) will more thoroughly assess the particular aspects of the seizures. When medications are clearly ineffective, the other types of therapy that can be considered are the ketogenic diet, brain surgery, and vagal nerve stimulation. Ketogenic diet The ketogenic diet is based on high-fat, low-carbohydrate, and low-protein meals. The ketogenic diet is named because of the production of ketones by the breakdown of fatty acids. The most common version of the diet involves long-chain triglycerides. These are present in whole cream, butter, and fatty meats. The ketogenic diet is administered with the support of a nutritionist with experience in this treatment modality. It is mostly used in children with medically intractable epilepsy and whose diet can be controlled. The ketogenic diet can be considered a pharmacologic treatment. As such, there are potential side effects that limit its tolerance. This includes hair thinning, lethargy, weight loss, kidney stones, and possibly cardiac problems. Sugar-free vitamin and mineral supplementation is necessary. The diet may not be appropriate for certain individuals, particularly in children, who may have certain metabolic diseases. Overall, the diet has been very helpful in the control of seizures in many patients. Roughly 50% of patients can hope to achieve complete control of seizures, 25% of the patients see improvements, and another 25% are non-responders. There are some patients who have an improvement in behavior. If the diet is well tolerated with good results, then it can be maintained for up to two years, followed by a careful gradual transition to regular meals.

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Epilepsy

Elizabeth Rudy, who suffers from epilepsy, sits hooked up to brain wave monitor. Her left hand strokes her seizurepredicting dog, Ribbon. (A/P Wide World Photos. Reproduced by permission.)

Epilepsy surgery Epilepsy surgery is an option in the attempt to either cure or significantly reduce the severity of medically resistant cases. It is thought that up to 100,000 patients in the United States could be potential candidates for a surgical treatment. However, only about 5,000 cases are performed throughout the United States annually. This is likely due to several factors, including the belief that any brain surgery is a last resort, the lack of awareness or understanding of the benefits of surgery, and the false hope that some medication will come along that will be effective. There are several kinds of surgery that are available depending on the nature of the seizure disorder. A list of operations that are utilized regularly for epilepsy include: • lobectomy • lesionectomy • corpus collosotomy • multiple subpial transection • hemispherectomy The type of surgery that is performed depends on the nature of the individual seizure disorder. If a seizure can

be localized to a particular area in the brain, then this abnormal region can potentially be surgically removed. Epileptic brain tissue is abnormal and its removal can provide a chance of a cure. Generally, surgery should be a consideration when the risk and benefits of it outweigh the long-term risks of uncontrolled epilepsy. The approach taken in any brain surgery for epilepsy is highly individualized and great care is taken to avoid injury to essential brain tissue. The most common epilepsy surgery performed is the temporal lobectomy. Brain tumors are frequently associated with seizures. In many cases, surgery to remove the tumor is planned so that regions that may be causing seizures are removed as well. However, in many cases, epilepsy surgery cannot be done. Vagus nerve stimulation Another non-medicinal approach to treating epilepsy is a novel method that became available in July 1997. The Food and Drug Administration (FDA) approved the use of the vagal nerve stimulator (VNS) as add-on therapy in patients who experience seizures of partial onset. The VNS is designed to intermittently deliver small electrical stimulations to a nerve in the neck called the vagus nerve.

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There are two vagal nerves, one on each side of the neck near the carotid arteries, making a pair of cranial nerves (there are 12 different paired cranial nerves). The vagus nerve carries information from the brain to many parts of the thoracic and abdominal organs. The nerve also carries information from these same organs back to the brain. VNS takes advantage of this fact and, by intermittent stimulation, there is an effect on many brain areas that can be involved in seizures. About 50% of patients experience at least 50% reduction in the frequency of their seizures. The responses to VNS range from complete control of seizures (less than 10% of patients) to no noticeable improvement. The device is not a substitute for epilepsy surgery and should be considered only after there is an evaluation for epilepsy surgery. The implantation of the device requires relatively minor surgery with two incisions, one in the neck and the other in the left upper chest area. The battery in the device lasts up to eight to ten years, after which the device can be replaced. Side effects of VNS therapy include voice hoarseness that typically does not impair communication. Like any surgery, there is an initial risk of infection, bleeding, and pain. Recovery takes a few weeks. Individuals can return to their usual activities once the incisions have healed.

Clinical trials The National Institute of Neurological Disorders and Stroke list a number of clinical trials. There are also a number of studies being conducted at a more basic science stage evaluating the role of the following in seizures and epilepsy: neurotransmitters, non-neuronal cells, and genetic factors. Treatment strategies including deep brain stimulation and intracranial early seizure detection devices are being studied at different stages.

expect that medications will control seizures in up to 60–70% of cases. However, in some of the more than 30% of medically intractable cases, epilepsy surgery can improve or even cure the problem. Overall, most patients have a good chance of controlling seizures with the available options of treatment. The goal of treatment is complete cessation of seizures since a mere reduction in seizure frequency and/or severity may continue to limit patients’ quality of life: they may not be able to drive, sustain employment, or be productive in school. Resources BOOKS

Browne, T. R., and G. L. Holmes. Handbook of Epilepsy, 2nd edition. Philadelphia: Lippincott Williams & Wilkins. 2000. Devinski, O. A Guide to Understanding and Living with Epilepsy. Philadelphia: F.A. Davis Company. 1994. Engel, J., Jr., and T. A. Pedley. Epilepsy: A Comprehensive Textbook. Philadelphia: Lippincott-Raven. 1998. Freeman, M. J., et al. The Ketogenic Diet: A Treatment for Epilepsy, 3rd Edition. New York: Demos Medical Publishing, 2000. Hauser, W. A., and D. Hesdorffer. Epilepsy: Frequency, Causes, and Consequences. New York: Demos Medical Publishing, 1990. Pellock, J. M., W. E. Dodson, and B. F. D. Bourgeois. Pediatric Epilepsy Diagnosis and Therapy, 2nd Edition. New York: Demos Medical Publishing, 2001. Santilli, N. Managing Seizure Disorders: A Handbook for Health Care Professionals. Philadelphia: LippincottRaven. 1996. Schachter, S. C., and D. Schmidt. Vagus Nerve Stimulation, 2nd Edition. Oxford, England: Martin Dunitz, 2003. Wyllie, E. The Treatment of Epilepsy: Principles and Practice, 3rd Edition. Philadelphia: Lippincott Williams & Wilkins, 2001. PERIODICALS

Prognosis The prognosis of epilepsy varies widely depending on the cause, severity, and patient’s age. Even individuals with a similar diagnosis may have different experiences with treatment. For example, in benign epilepsy of childhood with centrotemporal spikes (also called benign rolandic epilepsy), the prognosis is excellent with nearly all children experiencing remission by their teens. With childhood absence epilepsy, the prognosis is variable. In this case, the absence seizures become less frequent with time, but almost half of patients may eventually develop generalized tonic-clonic seizures. Overall, the seizures are responsive to an appropriate anticonvulsant. On the other hand, the seizures in Lennox-Gastaut syndrome are very difficult to control. In this case, however, the ketogenic diet can help. In seizures that begin in adulthood, one can 354

Kwan, P., and M. J. Brodie. “Early Identification of Refractory Epilepsy.” New England Journal of Medicine no. 342 (2000): 314–319. ORGANIZATIONS

American Epilepsy Society. 342 North Main Street, West Hartford, CT 06117-2507. 860.586.7505. . Epilepsy Foundation of America. 4351 Garden City Drive, Landover, MD 20785-7223. (800) 332-1000. . International League Against Epilepsy. Avenue Marcel Thiry 204, B-1200, Brussels, Belgium. + 32 (0) 2 774 9547; Fax: + 32 (0) 2 774 9690. .

Roy Sucholeiki, MD

Erb’s palsy see Brachial plexus injuries

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❙ Exercise Definition

Exercise is physical activity that is undertaken in order to improve one’s health. Physicians, physical therapists, and researchers have found that exercise plays an important role in the maintenance of brain, nerve, and muscle function in the human body. New research suggests that exercise may delay mental deterioration with age and disease, and perhaps even promote neurogenesis (nerve cell growth).

Description Health care professionals recommend regular exercise because it increases energy, contributes to overall health, improves sleep, increases life expectancy, and enhances lifestyle. In terms of specific medical disorders, exercise has been shown to prevent or delay the onset of coronary artery disease, bone loss and osteoporosis, some types of cancer, and stroke. Generally, exercise is categorized into the following four types: • Aerobic exercise focuses on strengthening the heart, lungs, and circulatory system. Its major goal is to increase the heart rate and breathing rate. Examples of aerobic exercise include jogging, bicycling, swimming, and racket sports. • Strength training focuses on strengthening muscles and joints. It also improves balance and increases metabolism. Weightlifting is the most common form of strength training. • Balance exercises are used to improve stability. They stimulate the vestibular system, which includes muscles, joints, sensory organs, the inner ear, and the brain. • Stretching exercises improve flexibility, which helps prevent injury during other forms of exercises and may decrease chronic pain. Stretching exercises include yoga, tai chi, and basic stretches. All four types of exercises have been found to be important to maintaining brain, nerve, and muscle health. Exercise and the brain Exercise is particularly beneficial to the health of the brain. It has long been known that exercise causes the endocrine system to release serotonin and dopamine, hormones in the brain that produce feelings of euphoria and

peacefulness. These hormones often allow people who exercise to think more clearly and perform mental tasks more easily. Exercise has also been successfully used as a treatment for depression, used in lieu of prescription antidepressants. A 2003 study on mice suggests that new brain cells can grow as a result of exercise. This neurogenesis, previously thought not to occur in adult mammals, is concentrated in the hippocampus, the part of the brain responsible for learning and spatial memory. In addition, the study found that the mice subjected to an exercise regimen had stronger synapses than the mice that were sedentary. Other research shows that nerve growth factors, called neurotropins, are stimulated by exercise. Finally, exercise increases blood flow to the brain, as well as collateral circulation, enhancing mental function and nerve cell stimulation. Exercise and aging Aging naturally affects a variety of processes in the human body. Exercise has many positive benefits that prevent or slow the age-related deterioration of brain, nerve, and muscle functions. In 2001, a study reported by the Mayo Clinic showed that regular exercise in older people slowed rates of mental deterioration, including Alzheimer’s disease and dementia. On tests of mental acuity, older people who exercised regularly performed just as well as younger people who did not exercise. Another study found that regular walking greatly slowed rates of mental decline in older women. Between the ages of 30 and 90, natural aging processes result in the loss of 15–25% of the brain tissue. In particular, losses are significant in the parts of the brain consisting of gray matter, which is associated with learning and memory. The February 2003 issue of Journal of Gerontology: Medical Sciences reported that this natural degradation of gray matter in older people was significantly decreased in people who exercised regularly compared to those who did not exercise. In the study, fitness levels were determined by treadmill-walking tests and tissue degradation was measured using magnetic resonance imaging (MRI). Balance is often affected as people age. Balance depends on input from the eyes, ears, and other sensory organs, all of which are affected by age. In addition, muscle strength and tone are required for balance. The natural aging process includes contraction of muscle tissue, and sedentary lifestyles only exacerbate the weakening of muscles. Joints supported by strong muscles are more stable than joints that are supported by weak muscles. Strength training, in particular, has the potential to counteract loss of muscle strength.

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Erb-Duchenne and Dejerine-Klumpke palsies see Brachial plexus injuries

Exercise

Physical therapy and the brain, nerves, and muscles Therapeutic exercises have been designed to enhance a variety of aspects of physical fitness in patients suffering from diseases and dysfunctions. Goals of physical therapy include improving circulation, coordination, balance, and respiratory capacity. Exercises may be geared toward mobilizing joints and releasing contracted muscles and tendons. Patients suffering from neurological disorders can be treated with a variety of physical therapies. For example, motor neuron damage or partial peripheral nerve damage may respond to a specific type of physical therapy called proprioceptive neuromuscular facilitation (PNF). PNF focuses on exercises that build muscle strength by applying resistance to muscle contraction. Patients who have experienced cerebrovascular accidents may undergo PNF combined with training for muscle strength, balance, and coordination. Multiple sclerosis is treated with PNF along with physical fitness training. Physical therapies for Parkinson disease focus on general physical fitness training, along with stretching exercises. Resources BOOKS

Putnam, Stephen C. Nature’s Ritalin for the Marathon Mind. Hinesburg, VT: Upper Access Book Publishers, 2001. Ratey, John. A User’s Guide to the Brain: Perception, Attention, and the Four Theaters of the Brain. Vancouver, WA: Vintage Books, 2002.

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OTHER

Effects on Neurologic Diseases and Mental Decline. Health and Age. (March 18, 2004). . Frankenfield, Gay. “Exercise May Improve Learning and Memory.” WebMD January 4, 2004 (March 18, 2004). . Lawrence, Star. “Train Your Brain with Exercise.” WebMD July 28, 2003 (March 18, 2004). . Warner, Jennifer. “Exercise Saves Brain Cells.” WebMD January 29, 2003 (March 18, 2004). . ORGANIZATIONS

Centers for Disease Control and Prevention, National Center for Chronic Disease Prevention and Health Promotion. Division of Nutrition and Physical Activity, 4770 Buford Highway, NE, Atlanta, GA 30341-3724. (888) CDC4NRG ((888) 232-4674). . The President’s Council on Physical Fitness and Sports. Department W, 200 Independence Ave., SW, Room 738-H, Washington, DC 20004. (202) 690-9000; Fax: (202) 690-5211. .

Juli M. Berwald

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F ❙ Fabry disease Definition

Fabry disease is a genetic condition that typically affects males. It is caused by deficiency of an enzyme, a chemical that speeds up another chemical reaction. Fabry disease can affect many parts of the body including the kidneys, eyes, brain, and heart. Pain in the hands and feet and a characteristic rash are classic features of this disease.

Description The symptoms of Fabry disease were first described by Dr. Johann Fabry and Dr. William Anderson in 1898. The enzyme deficiency that leads to the disease was identified in the 1960s. The symptoms of Fabry disease are variable. Some individuals with Fabry disease have severe complications, while others have very mild symptoms. The first sign of the disease may be a painful burning sensation in the hands and feet (acroparesthesias). A red rash, most commonly between the belly button and the knees (angiokeratoma) is also common. The outer portion of the eye (cornea) may also become clouded in individuals with Fabry disease. The progressive buildup of globotriaosylceramide can also lead to kidney problems and heart disease in adulthood.

Demographics Fabry disease affects approximately one in 40,000 live births. It occurs evenly among all ethnic groups. Almost always, only male children are affected. Although female carriers of the disease occasionally develop symptoms of the disease, it is rare for a female carrier to be severely affected.

Causes and symptoms Fabry disease is caused by a change (mutation) in the GLA gene. This gene is responsible for the production of the enzyme alpha-galactosidase A. Alpha-galactosidase A

normally breaks down globotriaosylceramide. Globotriaosylceramide is a natural substance in the body, made of sugar and fat. A mutation in the GLA gene leads to a decrease in alpha-galactosidase A activity which, in turn, leads to an excess of globotriaosylceramide. The excess globotriaosylceramide builds up in blood vessels (veins, arteries, and capillaries) and obstructs normal blood flow. It also builds up in parts of the skin, kidneys, heart, and brain. It is this buildup that inhibits normal function and leads to the symptoms associated with the disease. The gene that produces alpha-galactosidase A is located on the X chromosome. It is called the GLA gene. Since the GLA gene is located on the X chromosome, Fabry disease is considered to be X-linked. This means that it generally affects males. The signs and symptoms of Fabry disease vary. Some individuals with Fabry disease have many severe symptoms, while other individuals’ symptoms may be few and mild. The symptoms typically increase or intensify over time. This progression is caused by the slow buildup of globotriaosylceramide as the person ages. A painful burning sensation in the hands and feet (acroparesthesias) is one of the first symptoms of Fabry disease. This pain can be severe and may grow worse with exercise, stress, illness, extreme heat, or extreme cold. Another symptom of Fabry disease typically present during childhood is a red rash (angiokeratoma). This rash typically develops between the navel and the knees. Children with Fabry disease may also have a clouding of the outer most portion of the eye (cornea). This symptom is usually diagnosed by an eye doctor (ophthalmologist). The cloudiness may increase with time. A decreased ability to sweat is another common symptom of Fabry disease. Due to the progressive nature of Fabry disease, most affected individuals develop additional symptoms by age 40. The buildup of globotriaosylceramide in the heart can lead to heart problems. These heart problems can include changes in the size of the heart (left ventricular enlargement), differences in the heart beat, and leaky heart valves.

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Fabry disease is definitively made by measuring the activity of the alpha-galactosidase A enzyme. When the activity is very low, it is diagnostic of Fabry disease. This enzyme analysis can be performed through a blood test. Measuring the activity of the enzyme can also detect female carriers. Women who are carriers of Fabry disease have enzyme activity that is lower than normal.

Chromosome X

22

PIG-A: Paroxysomal nocternal hemoglobinuria

2 21

1 11

DMD: Duchenne muscular dystrophy Spondyloepiphyseal dysplasia

Prenatal diagnosis is possible by measuring the alphagalactosidase A activity in fetal tissue drawn by amniocentesis or chorionic villus sampling (CVS). Fetuses should be tested if the mother is a carrier. A woman is at risk of being a carrier if she has a son with Fabry disease or someone in her family has Fabry disease.

Renpenning syndrome Sutherland-Hann syndrome

p q

11 12

1

ATP7A: Menkes syndrome ATRX: Smith-Fineman-Myers syndrome

13

Treatment team A number of specialized practitioners are necessary to care for patients with Fabry disease. Depending on the specific manifestations, these specialists may include a dermatologist to treat skin problems; a neurologist to treat such complications as dizziness, seizure, stroke; an ophthalmologist to treat eye problems; a nephrologist to treat kidney problems; a cardiologist to treat heart problems. A pain specialist may be helpful, as well.

21 2 22 23 24

GLA: Fabry disease IL2RG: X-linked severe combined immunodeficiency

25 26 27 28

OCRL1: Lowe syndrome SGBS1: Simpson-Golabi-Behmel syndrome FMR1: Fragile X syndrome STA: Emery-Dreifuss muscular dystrophy X-linked hydrocephaly

Treatment

ALD: Adrenoleukodystrophy

Asplenia (x) KAL: Kallman syndrome (x)

Fabry disease, on chromosome X. (Gale Group.)

Mitral valve prolapse is a particular type of leaky heart valve that is common in Fabry disease, even in childhood. The excess globotriaosylceramide can also disrupt normal blood flow in the brain. In some cases this can cause dizziness, seizures, and stroke. The kidneys are other organs affected by Fabry disease. Kidney problems can lead to an abnormal amount of protein in the urine (proteinuria). Severe kidney problems can lead to kidney failure. Although the symptoms of Fabry disease usually occur in males, female carriers may occasionally exhibit symptoms of the disease. Some carriers experience pain in their hands and feet. Carrier females may also have proteinuria and clouding of their cornea. It is rare for a female to experience all of the symptoms associated with Fabry disease.

Diagnosis Initially, the diagnosis of Fabry disease is based on the presence of the symptoms. It should also be suspected if there is a family history of the disorder. The diagnosis of 358

There is currently no cure for Fabry disease. Until such time as enzyme replacement therapy is proven to be safe and effective, individuals with Fabry disease must rely on traditional treatments. Pain can be treated with medications such as carbamazepine and dilantin. Individuals with Fabry disease are recommended to have routine evaluations of their heart and kidneys. Some individuals with kidney disease require a special diet that is low in sodium and protein. Dialysis and kidney transplantation may be necessary for patients with severe kidney disease. Certain medications may reduce the risk of stroke. Finally, individuals with Fabry disease are recommended to avoid the situations that cause the pain in their hands and feet to grow worse. In some situations medication may be required to reduce the pain.

Clinical trials A number of clinical trials are underway. Some are studying the specific nervous system effects of the disase. Others are giving individuals with Fabry disease the alphagalactosidase A enzyme (Replagal) as a form of enzyme replacement therapy. If successful, this enzyme replacement therapy may reduce or eliminate the symptoms associated with Fabry disease. Clopidogrel, a blood thinner, is also being studied to see if its administration may decrease the rate/severity of such complications as stroke and heart attack.

GALE ENCYCLOPEDIA OF NEUROLOGICAL DISORDERS

Acroparesthesias hands and feet.

Painful burning sensation in

Amniocentesis A procedure performed at 16–18 weeks of pregnancy in which a needle is inserted through a woman’s abdomen into her uterus to draw out a small sample of the amniotic fluid from around the baby. Either the fluid itself or cells from the fluid can be used for a variety of tests to obtain information about genetic disorders and other medical conditions in the fetus. Angiokeratoma Skin rash comprised of red bumps. Rash most commonly occurs between the navel and the knees. Blood vessels General term for arteries, veins, and capillaries that transport blood throughout the body. Chorionic villus sampling (CVS) A procedure used for prenatal diagnosis at 10-12 weeks gestation. Under ultrasound guidance a needle is inserted either through the mother’s vagina or abdominal wall and a sample of cells is collected from around the fetus. These cells are then tested for chromosome abnormalities or other genetic diseases.

Prognosis The prognosis for individuals with Fabry disease is good, especially with the arrival of enzyme replacement therapy. Currently, affected individuals survive into adulthood with the symptoms increasing over time. Resources BOOKS

Desnick, Robert J., Yiannis Ioannou, and Christine Eng. “Galactosidase A Deficiency: Fabry Disease.” In The Molecular Bases of Inherited Disease. 8th ed. New York: McGraw Hill, 2001.

Cornea The transparent structure of the eye over the lens that is continuous with the sclera in forming the outermost protective layer of the eye. Dialysis Process by which special equipment purifies the blood of a patient whose kidneys have failed. Enzyme replacement therapy Giving an enzyme to a person who needs it for normal body function. It is given through a needle that is inserted into the body. Left ventricular enlargement Abnormal enlargement of the left lower chamber of the heart. Mitral valve prolapse A heart defect in which one of the valves of the heart (which normally controls blood flow) becomes floppy. Mitral valve prolapse may be detected as a heart murmur, but there are usually no symptoms. Mutation A permanent change in the genetic material that may alter a trait or characteristic of an individual, or manifest as disease, and can be transmitted to offspring. Proteinuria Excess protein in the urine.

National Organization for Rare Disorders (NORD). PO Box 8923, New Fairfield, CT 06812-8923. (203) 746-6518 or (800) 999-6673. Fax: (203) 746-6481. . WEBSITES

Fabry Disease Home Page. . Online Mendelian Inheritance in Man (OMIM). .

Holly Ann Ishmael, MS, CGC Rosalyn Carson-DeWitt, MD

ORGANIZATIONS

Alliance of Genetic Support Groups. 4301 Connecticut Ave. NW, Suite 404, Washington, DC 20008. (202) 966-5557. Fax: (202) 966-8553. . Deptartment of Human Genetics, International Center for Fabry Disease. Box 1497, Fifth Ave. at 100th St., New York, NY 10029. (866) 322-7963. . Fabry Support and Information Group. PO Box 510, 108 NE 2nd St., Suite C, Concordia, MO 64020. (660) 463-1355. . National Institute of Neurological Disorders and Stroke. 31 Center Drive, MSC 2540, Bldg. 31, Room 8806, Bethesda, MD 20814. (301) 496-5751 or (800) 352-9424. .

❙ Facial synkinesis Definition

Facial synkinesis is the involuntary movement of facial muscles that accompanies purposeful movement of some other set of muscles; for example, facial synkinesis may result in the mouth involuntarily closing or grimacing when the eyes are purposefully closed.

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Facial synkinesis

Key Terms

Fainting

Description

Treatment

Facial synkinesis occurs during recuperation from conditions or injuries that affect the facial nerve, for example during recovery from Bell’s palsy. During recovery, as the facial nerve tries to regenerate, some new nerve twigs may accidentally regrow in close proximity to muscles that they wouldn’t normally innervate (stimulate). Facial synkinesis may occur transiently, during recovery, or may become a permanent disability. As with all facial injuries or palsies, facial synkinesis can cause considerable emotional distress. Lack of control over one’s facial expressions is known to be a serious psychological stressor.

Causes and symptoms

Prognosis

Facial synkinesis can follow any injury or condition causing palsy or paralysis of the facial nerve. The most common associated disorder is Bell’s palsy; about 40% of all individuals who are recovering from Bell’s palsy will experience facial synkinesis during recovery. Other conditions that may prompt the development of facial synkinesis include stroke, head injury, birth trauma, head injury, trauma following tumor removal (such as acoustic neuroma), infection, Lyme disease, diabetes, and multiple sclerosis. Facial synkinesis can cause a number of abnormalities in the facial muscles. For example, when a patient with facial synkinesis tries to close his or her eyes, the muscles around the mouth may twitch or grimace. Conversely, when the patient tries to smile, the eyes may involuntarily close. The phenomenon of purposeful mouth movements resulting in involuntary eye closing is often referred to as “jaw winking.” Unfortunately, as with any facial deformity or disability, facial synkinesis carries with it a high risk of concomitant depression, anxiety, and disruption of interpersonal relationships and employment.

Diagnosis Diagnosis is usually apparent on physical examination. When the patient is asked to move certain facial muscles (i.e., smile), other facial muscles will be activated (e.g., the eyes may close involuntarily). When the underlying condition is unclear, a variety of tests may be required, such as CT or MRI scanning or EMG (electromyographic) testing to evaluate the functioning of the facial nerves and muscles.

Treatment team Facial synkinesis may be treated by neurologists or otorhinolaryngologists.

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Treatment may include: • surgery, to remove causative tumors or other sources of pressure on and damage to the facial nerve • steroid medications, to decrease inflammation of the facial nerve • facial exercises • electrical stimulation (this remains controversial, and may, in fact, worsen facial synkinesis in some patients) • intensive video-assisted, electromyographic feedback facial muscle retraining • injections of the paralytic agent botox into the muscle groups that are contracting involuntarily

The prognosis of facial synkinesis is quite variable, depending largely on the prognosis of the underlying condition that caused its development. Resources BOOKS

Goetz, Christopher G., ed. Textbook of Clinical Neurology. Philadelphia: W. B. Saunders Company, 2003. PERIODICALS

Armstrong, M. W., R. E. Mountain, and J. A. Murray. “Treatment of facial synkinesis and facial asymmetry with botulinum toxin type A following facial nerve palsy.” Clin Otolaryngol 21, no. 1 (February 1996): 15–20. Messé, S. R. “Oculomotor synkinesis following a midbrain stroke.” Neurology 57, no. 6 (September 2001): 1106–1107. Münevver, Çelik, Hulki Forta, and Çetin Vural. “The Development of Synkinesis after Facial Nerve Paralysis.” European Neurology 43 (2000): 147–151. Zalvan, C., B. Bentsianov, O. Gonzalez-Yanes, and A. Blitzer. “Noncosmetic uses of botulinum toxin.” Dermatol Clin 22, no. 2 (April 2004): 187–195. WEBSITES

Diels, H. Jacqueline. New concepts in Non-Surgical Facial Nerve Rehabilitation. Bell’s Palsy Infosite. (June 2, 2004). .

Rosalyn Carson-DeWitt, MD

❙ Fainting Definition

Fainting is a temporary loss of consciousness, weakness of muscles, and inability to stand up, all caused by sudden loss of blood flow to the brain. Fainting is a relatively common symptom caused by a variety of problems

GALE ENCYCLOPEDIA OF NEUROLOGICAL DISORDERS

Description Fainting is a common symptom, also called syncope, vasovagal attack, neurally mediated syncope (NMS), neurocardiogenic syncope, and vasodepressor or reflex mediated syncope. Most simple faints result from an overstimulation of the autonomic nervous system that results in a drop in blood pressure and a slowed heart rate. Both of these conditions decrease blood flow to the brain, which causes a feeling of lightheadedness (presyncope) or a complete loss of consciousness (syncope). Fainting usually occurs in people who are standing or sitting upright. A person about to faint may also feel nauseated, weak, and warm. The person may experience temporary visual impairment, headache, ringing in the ears, shortness of breath, sensation of spinning, tingling in the extremities, and incontinence. A person experiencing presyncope may also appear pale or bluish. When consciousness is lost, a person usually falls down. This allows for more blood flow to the brain, resulting in a return to consciousness, usually within a few minutes.

Causes Fainting is caused by a variety of factors, including stress, pain, overheating, dehydration, excessive sweating, exhaustion, hunger, alcohol, and drugs. Fainting may also be a side effect of some medications. A simple faint resulting from any of these factors is usually not a symptom of a neurological disorder. Some people faint when changing positions, a condition known as postural hypotension. When people with this condition move from a lying position to a standing or sitting position, the sudden pooling of blood in the legs may cause a temporary decrease in blood circulation to the brain, causing a faint. This condition is common in elderly people who have been bedridden for some time and in people with poor muscle tone. Some faints indicate serious disorders of the nervous or circulatory systems. Nervous system disorders that cause faints include acute or subacute dysautonomia, postganglionic autonomic insufficiency, and chronic preganglionic autonomic insufficiency. Fainting may also signal an irregular pattern of nervous stimulation such as micturition syncope (fainting while urinating), glossopharyngeal neuralgia (irritation of the ninth cranial nerve, causing pain in the tongue, throat, ear, and tonsils), cough syncope (fainting while coughing violently), and stretch syncope (fainting when stretching arms and neck). Faints

can also indicate problems with the regulation of blood pressure and heart rate, and with disorders such as diabetes, alcoholism, malnutrition, and amyloidosis. Fainting can signal circulatory problems, particularly those that disrupt blood flow to the brain, as well as problems with the electrical impulses that control the heart, problems with the sinus node of the heart, heart arrhythmia, blood clots in the lung, a narrowing of the aorta, or other anatomical irregularities in the heart. Additionally, hyperventilation, usually associated with anxiety or panic, can result in a faint.

Diagnosis Patients visiting a doctor because of fainting will usually have their blood pressure checked when they are lying down and then again after they stand up. If there is a significant decrease in blood pressure, it may indicate postural hypotension. A more sophisticated form of this blood pressure test is a tilt test, during which a person is strapped to a board that is rotated from the horizontal to the vertical position. Blood pressure is measured in both positions; an extreme drop indicates postural hypotension. To test for circulatory problems, a physician may also use an electrocardiogram (EKG) to test for abnormalities of the heart beat. Exercise stress tests or wearing a Holter monitor for a day may also be performed to check for disorders of the heart. Fainting suspected to be caused by neurological disorders requires additional tests and evaluation by a neurologist.

Treatment If a person faints while sitting, the body weight should be supported and the head positioned between the knees. If a person faints while standing, the individual should be carefully lowered to the ground and the legs elevated. Any tight clothes, including belts and collars, should be loosened. The head should be turned to the side so that the tongue does not obstruct the trachea and any vomit can be cleared from the airway. If the person stops breathing, cardiopulmonary resuscitation (CPR) should be started and a call should be placed to emergency medical services. A person who has fainted may benefit from cold compresses to the head and neck. After the person regains consciousness, he or she should remain lying or sitting for some time and should stand up only if no feeling of lightheadedness persists. A person who faints often will be treated for the underlying condition. Often, medications are used to control fainting; however, other methods may be helpful as well. In some people, changing to a high-salt diet or wearing support hose to keep blood from pooling in the legs prevents fainting. Some people may be able to prevent fainting by keeping glucose levels at a more constant level or

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Fainting

relating to changes in blood pressure. The American Heart Association reports that fainting is responsible for 3% of all visits to emergency rooms and 6% of all admissions to hospitals.

Fatigue

Familial hemangioma see Cerebral cavernous malformation

Key Terms Autonomic nervous system The part of the nervous system that controls so-called involuntary functions, such as heart rate, salivary gland secretion, respiratory function, and pupil dilation. Postural hypotension A drop in blood pressure that causes faintness or dizziness and occurs when an individual rises to a standing position. Also known as orthostatic hypotension. Syncope A loss of consciousness over a short period of time, caused by a temporary lack of oxygen in the brain.

by learning breathing techniques to prevent hyperventilation. Another technique for preventing faints is drinking enough fluid to keep blood volume high. Resources BOOKS

Icon Health Publications. The Official Patient’s Sourcebook on Syncope: A Revised and Updated Directory for the Internet Age. San Diego, CA: ICON Group International, 2003. OTHER

DeNoon, Daniel. Fainting Is a Serious Symptom. WebMD. January 14, 2002 (March 18, 2004). . Fainting. FamilyDoctor. March, 2002 (March 18, 2004). . Grayson, Charlotte. Understanding Fainting—The Basics. WebMD. January 1, 2002 (March 18, 2004). . The Mayo Clinic Staff. Simple Faint (Vasovagal Syncope). The Mayo Clinic. June 26, 2003 (March 18, 2004). . Syncope. American Heart Association. December 22, 2003 (March 18, 2004). . ORGANIZATIONS

American Heart Association National Center. 7272 Greenville Avenue, Dallas, TX 75231. (800) AHA-USA1. . National Heart, Blood and Lung Institute. P.O. Box 30105, Bethesda, MD 20824-0105. (301) 592-8573; Fax: (301) 592-8563. . National Institute of Neurological Disorders and Stroke. P.O. Box 5801, Bethesda, MD 20824. (301) 496-5751 or (800) 352-9424. .

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Familial spastic paralysis see Hereditary spastic paraplegia

❙ Fatigue Definition

Fatigue may be defined as a subjective state in which one feels tired or exhausted, and in which the capacity for normal work or activity is reduced. There is, however, no commonly accepted definition of fatigue when it is considered in the context of health and illness. This lack of definition results from the fact that a person’s experience of fatigue depends on a variety of factors. These factors include culture, personality, the physical environment (light, noise, vibration), availability of social support through networks of family members and friends, the nature of a particular fatiguing disease or disorder, and the type and duration of work or exercise. The experience of fatigue associated with disease will be different for someone who is clinically depressed, is socially isolated, and is out of shape, as compared to another person who is not depressed, has many friends, and is aerobically fit.

Description Fatigue is sometimes characterized as normal or abnormal. For example, the feeling of tiredness or even exhaustion after exercising is a normal response and is relieved by resting; many people report that the experience of ordinary tiredness after exercise is pleasant. Moreover, this type of fatigue is called “acute” since the onset is sudden and the desired activity level returns after resting. On the other hand, there is fatigue that is not perceived as ordinary, that may develop insidiously over time, is unpleasant or seriously distressing, and is not resolved by rest. This kind of fatigue is abnormal and is called “chronic.” Some researchers regard fatigue as a defense mechanism that promotes the effective regulation of energy expenditures. According to this theory, when people feel tired they take steps to avoid further stress (physical or emotional) by resting or by avoiding the stressor. They are then conserving energy. Since chronic fatigue is not normal, however, it is a common symptom of some mental disorders, a variety of physical diseases with known etiologies (causes), and medical conditions that have no biological markers although they have recognizable syndromes (patterns of symptoms and signs).

GALE ENCYCLOPEDIA OF NEUROLOGICAL DISORDERS

Risk factors Fatigue is a common experience. It is one of the top ten symptoms that people mention when they visit the doctor. Some people, however, are at higher risk for developing fatigue. The risk for women is about 1.5 times the risk for men, and the risk for people who do not exercise is twice that of active people. Some researchers question whether women really are at higher risk, since women are more likely than men to go to the doctor with health problems; also, men are less likely to admit they feel fatigued. Other risk factors include obesity, smoking, use of alcohol, high stress levels, depression, anxiety, and low blood pressure. Having low blood pressure is usually considered desirable in the United States, but is regarded as a treatable condition in other countries. Low blood pressure or postural hypotension (sudden lowering of blood pressure caused by standing up) may cause fatigue, dizziness, or fainting.

Major sources of chronic fatigue Disease There are many diseases and disorders in which fatigue is a major symptom—for example, cancer, cardiovascular disease, emphysema, multiple sclerosis, rheumatic arthritis, systemic lupus erythematosus, HIV/AIDS, infectious mononucleosis, chronic fatigue syndrome, and fibromyalgia. The reasons for the fatigue, however, vary according to the organ system or body function affected by the disease. Physical reasons for fatigue include: • Circulatory and respiratory impairment. When the patient’s breathing and blood circulation are impaired, or when the patient has anemia (low levels of red blood cells), body tissues do not receive as much oxygen and energy. Consequently, the patient experiences a general sense of fatigue. Fatigue is also an important warning sign of heart trouble; it precedes 30–55% of myocardial infarctions (heart attacks) and sudden cardiac deaths. • Infection. Microorganisms that disturb body metabolism and produce toxic wastes cause disease and lead to fatigue. Fatigue is an early primary symptom of chronic, nonlocalized infections found in such diseases as acquired immune deficiency syndrome (AIDS), Lyme disease, and tuberculosis.

Fatigue

Fatigue is sometimes described as being primary or secondary. Primary fatigue is a symptom of a disease or mental disorder, and may be part of a cluster of such symptoms as pain, fever, or nausea. As the disease or disorder progresses, however, the fatigue may be intensified by the patient’s worsening condition, by the other disease symptoms, or by the surgical or medical treatment given to the patient. This subsequent fatigue is called secondary.

KEY TERMS Biological marker An indicator or characteristic trait of a disease that facilitates differential diagnosis (the process of distinguishing one disorder from other, similar disorders). Deconditioning Loss of physical strength or stamina resulting from bed rest or lack of exercise. Electrolytes Substances or elements that dissociate into electrically charged particles (ions) when dissolved in the blood. The electrolytes in human blood include potassium, magnesium, and chloride. Metabolism The group of biochemical processes within the body that release energy in support of life. Stress A physical and psychological response that results from being exposed to a demand or pressure. Syndrome A group of symptoms that together characterize a disease or disorder.

• Nutritional disorders or imbalances. Malnutrition is a disorder that promotes disease. It is caused by insufficient intake of important nutrients, vitamins, and minerals; by problems with absorption of food through the digestive system; or by inadequate calorie consumption. Protein-energy malnutrition (PEM) occurs when people do not consume enough protein or calories; this condition leads to wasting of muscles and commonly occurs in developing countries. In particular, young children who are starving are at risk of PEM, as are people recovering from major illness. In general, malnutrition damages the body’s immune function and thereby encourages disease and fatigue. Taking in too many calories for the body’s needs, on the other hand, results in obesity, which is a predictor of many diseases related to fatigue. • Dehydration. Dehydration results from water and sodium imbalances in body tissues. The loss of total body water and sodium may be caused by diarrhea, vomiting, bed rest, overexposure to heat, or exercise. Dehydration contributes to muscle weakness and mental confusion; it is a common and overlooked source of fatigue. Once fatigued, people are less likely to consume enough fluids and nutrients, which makes the fatigue and confusion worse. • Deconditioning. This term refers to generalized organ system deterioration resulting from bed rest and lack of exercise. In the 1950s and 1970s, the National Aeronautics and Space Administration (NASA) studied the effects

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of bed rest on healthy athletes. The researchers found that deconditioning occurred rapidly (within 24 hours) and led to depression and weakness. Even mild exercise can counteract deconditioning, however, and it has become an important means of minimizing depression and fatigue resulting from disease and hospitalization. • Pain. When pain is severe enough, it may disrupt sleep and lead to the development of such sleep disorders as insomnia or hypersomnia. (Insomnia is the term for having difficulty falling and/or staying asleep. Hypersomnia refers to excessive sleeping.) In general, disrupted sleep is not restorative; people wake up feeling tired, and as a result their pain is worsened and they may become depressed. Furthermore, pain may interfere with movement or lead to too much bed rest, which results in deconditioning. Sometimes pain leads to social isolation because the person cannot cope with the physical effort involved in maintaining social relationships, or because family members are unsympathetic or resentful of the ill or injured person’s reduced capacity for work or participation in family life. All of these factors worsen pain, contributing to further sleep disruption, fatigue, and depression. • Stress. When someone experiences ongoing pain and stress, organ systems and functional processes eventually break down. These include cardiovascular, digestive, and respiratory systems, as well as the efficient elimination of body wastes. According to the American Psychiatric Association, various chronic diseases are related to stress, including regional enteritis (intestinal inflammation), ulcerative colitis (a disease of the colon), gastric ulcers, rheumatoid arthritis, cardiac angina, and dysmenorrhea (painful menstruation). These diseases deplete the body’s levels of serotonin (a neurotransmitter important in the regulation of sleep and wakefulness, as well as depression), and endorphins (opiate-like substances that moderate pain). Depletion of these body chemicals leads to insomnia and chronic fatigue. • Sleep disorders. There are a variety of sleep disorders that cause fatigue, including insomnia, hypersomnia, sleep apnea, and restless legs syndrome. For example, hypersomnia may be the result of brain abnormalities caused by viral infections. Researchers studying the aftermath of infectious mononucleosis proposed that exposure to viral infections might change brain function with the effect of minimizing restorative sleep. Another common disorder is sleep apnea, in which the patient’s breathing stops for at least 10 seconds, usually more than 20 times per hour. Snoring is common. People may experience choking and then wake up gasping for air; they may develop daytime hypersomnia (daytime sleepiness) to compensate. Sleep apnea is associated with aging, weight gain, and depression. It is also a risk factor for

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stroke and myocardial infarctions. Restless legs syndrome is a condition in which very uncomfortable sensations in the patient’s legs cause them to move and wake up from sleep, or keep them from falling asleep. All of these disorders reduce the quality of a person’s sleep and are associated with fatigue. Fibromyalgia and chronic fatigue syndrome Fibromyalgia (also known as myofascial syndrome or fibrositis) is characterized by painful and achy muscles, tendons, and ligaments. There are 18 locations on the body where patients typically feel sore. These locations include areas on the lower back and along the spine, neck, and thighs. A diagnostic criterion for fibromyalgia (FM) is that at least 11 of the 18 sites are painful. In addition to pain, people with FM may experience sleep disorders, fatigue, anxiety, and irritable bowel syndrome. Some researchers maintain, however, that when fatigue is severe, chronic, and persistent, FM is indistinguishable from chronic fatigue syndrome (CFS). The care that patients receive for FM or CFS depends in large measure on whether they were referred to a rheumatologist (a doctor who specializes in treating diseases of the joints and muscles), neurologist, or psychiatrist. Some doctors do not accept CFS (also known as myalgic encephalomyelitis) as a legitimate medical problem. This refusal is stigmatizing and distressing to the person who must cope with disabling pain and fatigue. Many people with CFS may see a number of different physicians before finding one who is willing to diagnose CFS. Nevertheless, major health agencies such as the Centers for Disease Control (CDC) in the United States have studied the syndrome. As a result, a revised CDC case definition for CFS was published in 1994 that lists major and minor criteria for diagnosis. The major criteria of CFS include the presence of chronic and persistent fatigue for at least six months; fatigue that does not improve with rest; and fatigue that causes significant interference with the patient’s daily activities. Minor criteria include such flu-like symptoms as fever, sore throat, swollen lymph nodes, myalgia (muscle pain), difficulty with a level of physical exercise that the patient had performed easily before the illness, sleep disturbances, and headaches. Additionally, people often have difficulty concentrating and remembering information and they experience extreme frustration and depression as a result of the limitations imposed by CFS. The prognosis for recovery from CFS is poor, although the symptoms are manageable. Psychological disorders While fatigue may be caused by many organic diseases and medical conditions, it is a chief complaint for several mental disorders, including generalized anxiety

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GENERALIZED ANXIETY DISORDER

People are diagnosed as having generalized anxiety disorder (GAD) if they suffer from overwhelming worry or apprehension that persists, usually daily, for at least six months, and if they also experience some of the following symptoms: unusual tiredness, restlessness and irritability, problems with concentration, muscle tension, and disrupted sleep. Such stressful life events as divorce, unemployment, illness, or being the victim of a violent crime are associated with GAD, as is a history of psychiatric problems. Some evidence suggests that women who have been exposed to danger are at risk of developing GAD; women who suffer loss are at risk of developing depression, and women who experience danger and loss are at risk of developing a mix of both GAD and depression. While the symptoms of CFS and GAD overlap, the disorders have different primary complaints. Patients with CFS complain primarily of tiredness, whereas people with GAD describe being excessively worried. In general, some researchers believe that anxiety contributes to fatigue by disrupting rest and restorative sleep. DEPRESSION

In the fourth edition of the Diagnostic and Statistical Manual of Mental Disorders (DSM-IV), the presence of depressed mood or sadness, or loss of pleasure in life, is an important diagnostic criterion for depression. Daily fatigue, lack of energy, insomnia, and hypersomnia are indicators of a depressed mood. The symptoms of depression overlap with those of CFS; for example, some researchers report that 89% of people with depression are fatigued, as compared to 86–100% of people with CFS. The experience of fatigue, however, seems to be more disabling with CFS than with depression. Another difference between CFS and depression concerns the onset of the disorder. Most patients with CFS experience a sudden or acute onset, whereas depression may develop over a period of weeks or months. Also, while both types of patients experience sleep disorders, CFS patients tend to have difficulty falling asleep, whereas depressed patients tend to wake early in the morning. Some researchers believe that there is a link between depression, fatigue, and exposure to too much REM sleep. There are five distinct phases in human sleep. The first two are characterized by light sleep; the second two by a deep restorative sleep called slow-wave sleep; and the last by rapid eye movement, or REM, sleep. Most dreams occur during REM sleep. Throughout the night, the intervals of REM sleep increase and usually peak around 8:30 A.M. A

sleep deprivation treatment for depression involves reducing patients’ amount of REM sleep by waking them around 6:00 A.M. Researchers think that some fatigue associated with disease may be a form of mild depression and that reducing the amount of REM sleep will reduce fatigue by moderating depression.

Managing fatigue The management of fatigue depends in large measure on its causes and the person’s experience of it. For example, if fatigue is acute and normal, the person will recover from feeling tired after exertion by resting. In cases of fatigue associated with influenza or other infectious illnesses, the person will feel energy return as they recover from the illness. When fatigue is chronic and abnormal, however, the doctor will tailor a treatment program to the patient’s needs. There are a variety of approaches that include: • Aerobic exercise. Physical activity increases fitness and counteracts depression. • Hydration (adding water). Water improves muscle turgor, or tension, and helps to carry electrolytes. • Improving sleep patterns. The patient’s sleep may be more restful when its timing and duration are controlled. • Pharmacotherapy (treatment with medications). The patient may be given various medications to treat physical diseases or mental disorders, to control pain, or to manage sleeping patterns. • Psychotherapy. There are several different treatment approaches that help patients manage stress, understand the motives that govern their behavior, or change maladaptive ideas and negative thinking patterns. • Physical therapy. This form of treatment helps patients improve or manage functional impairments or disabilities. In addition to seeking professional help, people can understand and manage fatigue by joining appropriate self-help groups, reading informative books, seeking information from clearinghouses on the Internet, and visiting websites maintained by national organizations for various diseases. Resources BOOKS

Beers, Mark H., and Robert Berkow, eds. The Merck Manual of Diagnosis and Therapy, 17th ed. Whitehouse Station, NJ: Merck Research Laboratories, 1999. Glaus, A. Fatigue in Patients with Cancer: Analysis and Assessment. Recent Results in Cancer Research, no. 145. Berlin, Germany: Springer-Verlag, 1998.

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disorder and clinical depression. Moreover, mental disorders may coexist with physical disease. When there is considerable symptom overlap, the differential diagnosis of fatigue is especially difficult.

Febrile seizures

Hubbard, John R., and Edward A. Workman, eds. Handbook of Stress Medicine: An Organ System Approach. Boca Raton, FL: CRC Press, 1998. Natelson, Benjamin H. Facing and Fighting Fatigue: A Practical Approach. New Haven, CT: Yale University Press, 1998. Winningham, Maryl L., and Margaret Barton-Burke, eds. Fatigue in Cancer: A Multidimensional Approach. Sudbury, MA: Jones and Bartlett Publishers, 2000. PERIODICALS

Natelson, Benjamin H. “Chronic Fatigue Syndrome.” JAMA: Journal of the American Medical Association 285, no. 20 (May 23–30 2001): 2557–59. ORGANIZATIONS

MEDLINEplus Health Information. U.S. National Library of Medicine, 8600 Rockville Pike, Bethesda, MD 20894. (888) 346-3656. . National Chronic Fatigue Syndrome and Fibromyalgia Association. P.O. Box 18426, Kansas City, MO 64133. (816) 313-2000.

Children with febrile seizures often lose consciousness and shake, moving limbs on both sides of the body. Less commonly, children become rigid or have twitches on only one side of the body.

Demographics About 2–5% of all children experience a febrile seizure and about 25% of these children have a first-degree relative with history of febrile seizures. There is a slightly higher prevalence among boys, and no ethnic differences have been reported. Less than 5% of children with febrile seizures will eventually develop epilepsy.

Causes and symptoms

Tanja Bekhuis, PhD Rosalyn Carson-DeWitt, MD

❙ Febrile seizures Definition

Febrile seizures are the most common type of convulsions in infants or small children and are triggered by fever. It is not in the strict sense an epilepsy syndrome but rather a symptom of a febrile illness, and it normally affects children between three months and five years of age, mainly toddlers. During a febrile seizure, a child may lose consciousness and move or shake the limbs. The seizure itself is normally harmless and does not cause brain damage. A child who experiences a seizure in the setting of a fever should be taken to the hospital so that any serious causes of the fever can be evaluated.

Description Febrile seizures (or convulsions) occur mainly in children between three months and five years of age and are associated with a fever of any cause. Toddlers are most commonly affected and there is a tendency for febrile seizures to run in families. These seizures are associated with fevers that rapidly rise to temperature up to or above 102°F, but they can also occur with lower temperatures. There are two types of febrile seizures: simple (or benign) and complex. Benign febrile seizures account for 366

80–85% of all febrile seizures, and last less than 15 minutes. They usually do not recur within 24 hours. Complex febrile seizures, which suggest a more serious illness, account for 15–20% of all cases, last more than 15 minutes, and can recur within 24 hours.

The exact role of the fever in the development of seizures is not clear. However, it is known that viral infections are the most common cause of fever in children with a first febrile seizure who are admitted to hospitals, mainly caused by viruses like herpes and influenza. Meningitis causes less than 1% of febrile seizures, but should be investigated to rule out this serious infection, especially in children less than one year old or those who continue to appear ill after the fever subsides. Seizures that occur after immunizations are likely to be the febrile type due to temperature elevation, particularly those after the DTP (diphtheria, pertussis, tetanus) and measles immunizations. Upper respiratory tract infections accompanied by high fever, in combination with a low seizure threshold, can often affect infants and young children and, thus, account for the most common cause of these convulsions. In a few studies, children with febrile seizures have been found to have decreased zinc levels in both the serum and the cerebrospinal fluid, which is the fluid that bathes the brain and the spinal cord. Deprivation of zinc may play a role in the seizures. Children with iron-deficiency anemia have been shown to have febrile seizures at a higher rate than nonanemic children. There is a positive family history in up to 31% of all cases of febrile seizures, although the exact mode of inheritance is not known and varies among families. It has long been recognized that there is a genetic component for the susceptibility to this type of seizure; this may be caused by mutations in several genes, especially the FB4 gene. Febrile seizures typically begin with a sudden contraction of muscles on both sides of the body, usually facial muscles, trunk, arms, and legs. The force of the

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Epilepsy A disorder of the central nervous system characterized by seizures. Meningitis Inflammation of the meninges, the membranes that surround the brain and spinal cord. Seizure Abnormal electrical discharge of neurons in the brain, often resulting in abnormal body movements or behaviors.

muscle contraction may cause the child to emit an involuntary cry or moan. The child falls, if standing, and may bite the tongue. Urinary incontinence and vomiting can occur. The child will not breathe, and may turn blue. Children cannot respond to any stimuli, and loss of consciousness, hallucinations, confusion, and feelings of fear or other emotions may occur. Focal seizures (those without loss of consciousness) involving only a part of the body are less common, and might become generalized, affecting the whole body.

Diagnosis The first action of the physician is to stop the fever and find its cause(s). Physicians may ask about previous seizures without a fever, which can indicate that the child is more likely to have an underlying seizure disorder such as epilepsy rather than a febrile seizure. Physicians also consider the family history of seizures, febrile or otherwise, and must investigate any known nervous disorder in the child, such as developmental delay or severe head injury. Any medication the child has taken is suspicious, and the possibility of drug reaction or poisoning may also be considered. It is important to rule out any infectious disease as the first cause of a seizure, especially meningitis. In the case of meningitis, the child appears particularly ill, shows neck rigidity, has an unusually long period of drowsiness after the seizure, and experiences a complex febrile seizure (often prolonged and repeated). Lumbar puncture (commonly known as a spinal tap) can be performed in this case to examine the cerebrospinal fluid for indications of meningitis. Other tests such as blood tests, urine tests, and x rays may be used in diagnosing the cause of fever.

During the acute phase of the seizure, the main objective is to keep the child in a position on his or her side or stomach to avoid aspiration of saliva or vomit and avoid injuries. The child should be placed on the floor or in a safe area, and all dangerous objects must be removed. A child having a seizure should not be restrained. If the child vomits, or if saliva and mucus build up in the mouth, a side posture should be used. It is also important that parents do not force anything into the child’s mouth, as this could result in breaking teeth. Also, tongue swallowing will not occur. If the child inadvertently bites the tongue, it will heal. Any tight clothing should be removed, especially around the neck. Because the seizure occurs in the setting of a fever, the main target of therapy is to bring the fever down. Removing the clothes and applying cool washcloths to the child’s neck and face may help, and acetaminophen or ibuprofen suppositories, if available, may control the elevated temperature. Rarely, a child may experience a persistent seizure, which could evolve into what is called status epilepticus. Airway management and anticonvulsivants are the first line of treatment during this medical emergency. The most commonly used medication includes benzodiazepines such as lorazepan (Ativan) and diazepam (Valium). An intravenous line is usually placed in the vein because it is the fastest and most reliable means of drug administration.

Recovery and rehabilitation Children are normally drowsy or in a state of confusion after a seizure, but become responsive within 15–30 minutes. A simple febrile seizure stops by itself within a few seconds to 10 minutes, usually followed by a brief period of drowsiness or confusion. In this case, an antiseizure medication may not be required. After a seizure, the child is twitchy, with jerks of the arms and legs.

Clinical trials As of early 2004, there are no open clinical trials for febrile seizures at the National Institutes of Health (NIH). However, the National Institute of Neurological Disorders and Stroke (NINDS), a part of the NIH, often sponsors research on febrile seizures in medical centers throughout the United States.

Treatment team A pediatrician is normally the first physician to be seen, and a neurologist should be considered for those cases in which a neurological disorder is thought to be the cause of the seizure rather than the fever.

Prognosis About 35% of children who have had a febrile seizure will have another one with a subsequent fever. Of those who do, about 50% will have a third seizure. Few children have more than three seizure episodes. A child is more

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Key Terms

Treatment

Felbamate

likely to fall in the group that has more than one febrile seizure if there is a family history, if the first seizure happened before 12 months of age, or if the seizure happened with a fever below 102°F. Seizures occur at the time the brain is sensitive to the effects of temperature and often cause parents great anxiety. As the onset is dramatic, parents are afraid their children will die or undergo brain damage. However, simple febrile seizures are harmless and they do not cause death, brain damage, epilepsy, mental retardation, or learning difficulties.

Special concerns Parental anxiety or other factors may cause a child to be placed on long-term anticonvulsant medicine. This will not benefit the patient. Children with the possibility of having a second seizure should not engage in activities that are potentially harmful, such as taking unsupervised baths or climbing higher than 5 ft (1.5 m) off the ground. Resources

Felbamate is thought to decrease abnormal activity and excitement within the central nervous system (CNS) that may trigger seizures. While felbamate controls some types of seizures associated with epilepsy, there is no known cure for the disorder. Felbamate has shown effectiveness in controlling partial seizures in adults when prescribed alone. When prescribed with other antiepileptic medicines, felbamate has shown effectiveness in managing the intractable (difficult to control) seizures of Lennox-Gastaut syndrome in children.

Description In the United States, felbamate is sold under the brand name Felbatol and FBM. Felbamate acts to depress CNS function; however the precise mechanisms by which it exerts its therapeutic effects in the prevention of seizures is unknown.

Recommended dosage

BOOKS

Baram, Tallie Z., and Shlomo Shinnar. Febrile Seizures. New York: Academic Press, 2001. Icon Health Publications Staff. The Official Parent’s Sourcebook on Febrile Seizures: A Revised and Updated Directory for the Internet Age. San Diego: Icon Group International, 2002. PERIODICALS

Baumann, R. J., and P. K. Duffner. “Treatment of Children with Simple Febrile Seizures: The AAP Practice Parameter.” Pediatr Neurol 23 (2000): 11–17. OTHER

“NINDS Febrile Seizures Information Page.” National Institute of Neurological Disorders and Stroke. March 4, 2004 (April 27, 2004). . ORGANIZATIONS

Epilepsy Foundation. 4351 Garden City Drive, Landover, MD 20785-7223. (301) 459-3700 or (800) 332-1000; Fax: (301) 577-2684. [email protected]. .

Marcos do Carmo Oyama Iuri Drumond Louro, MD, PhD

❙ Felbamate

Felbamate is taken by mouth and is available in tablet or oral suspension form. Adult patients usually take felbamate three to four times daily. The typical total daily dose for an adult or teenager over 14-years-old ranges from 1200 mg to 3600 mg. Treatment including felbamate is appropriate for some children with intractable seizures. The typical total daily dosage formula for a child is between 15 mg and 45 mg per kilogram of body weight. Beginning a course of treatment which includes felbamate requires a gradual dose-increasing regimen. Patients typically take a reduced dose at the beginning of treatment. The prescribing physician will determine the proper beginning dosage and may raise a patient’s daily dosage gradually over the course of several weeks. It may take several weeks to realize the full benefits of felbamate. It is important to not take a double dose of felbamate. If a daily dose is missed, take it as soon as possible. However, if it is almost time for the next dose, then skip the missed dose. When ending treatment for epilepsy that includes felbamate, physicians typically direct patients to gradually taper their daily dosages. Stopping the medicine suddenly may cause seizures to return or occur more frequently.

Precautions

Definition

Felbamate is an anticonvulsant indicated for the control of seizures in the treatment of epilepsy, a neurological dysfunction in which excessive surges of electrical energy are emitted in the brain. 368

Purpose

Prior to initiating therapy with felbamate, blood tests to check for anemia, infection, and liver function will likely be performed. Periodic blood tests are necessary to monitor liver and bone marrow function while receiving felbamate therapy, and for a period after the drug is discontinued.

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Key Terms

• nosebleed

Epilepsy A disorder associated with disturbed electrical discharges in the central nervous system that cause seizures.

• yellow tint to eyes or skin

Seizure A convulsion, or uncontrolled discharge of nerve cells that may spread to other cells throughout the brain, resulting in abnormal body movements or behaviors.

• weakness and fatigue

Felbamate may not be suitable for persons with a history of stroke, anemia, liver or kidney disease, mental illness, diabetes, high blood presure, angina (chest pain), irregular heartbeats, or other heart problems. Before beginning treatment with felbamate, patients should notify their physician if they consume a large amount of alcohol, have a history of drug use, are pregnant, nursing, or plan on becoming pregnant. Research in animals indicates that felbamate may inhibit fetal growth and development. Patients who become pregnant while taking felbamate should contact their physician. Consult a physician before taking felbamate with certain non-perscription medications. Patients should avoid alcohol and CNS depressants (medicines that can make one drowsy or less alert, such as antihistimines, sleep medications, and some pain medications) while taking felbamate.

Side effects Patients should discuss with their physicians the risks and benefits of treatment including felbamate before taking the medication. Dizziness and nausea are the most frequently reported side effects. Most mild side effects do not require medical treatment, and may diminish with continued use of the medication. Additional possible mild side effects include anorexia (loss of appetite), vomiting, insomnia, headache, and sleepiness. If any symptoms persist or become too uncomfortable, the prescribing physician should be consulted. Felbamate has been implicated as the cause of serious side effects, including plastic anemia (bone marrow failure) and liver failure. It is estimated that one in every 3,600 to 5,000 patients taking felbamate will eventually develop aplastic anemia, and the fatality rate of complicating aplastic anemia is nearly 30%. For this reason, felbamate is prescribed seldomly, and only after other medications have failed to control seizures. Persons taking felbamate who experience any of the following symptoms should immediately contact a physician:

Fisher syndrome

• rash or purple spots on skin

• bruising easily • signs of infection

Interactions Felbamate should be used with other other seizure prevention medications (anticonvulsants or anti-epileptic drugs [AEDs]), only if prescribed by a physician. Felbamate increases blood levels of phenytoin (Dilantin) and valproic acid (Depekene), while reducing blood levels of carbamazepine (Tegretol). Felbamate, like many other anticonvulsants, may decrease the effectiveness of oral contraceptives (birth control pills) or contraceptives containing estrogen. Resources BOOKS

Devinsky, Orrin, M.D. Epilepsy: Patient and Family Guide, 2nd. ed. Philadelphia: F. A. Davis Co., 2001. Weaver, Donald F. Epilepsy and Seizures: Everything You Need to Know. Toronto: Firefly Books, 2001. OTHER

Dodson, W. Edwin. M.D. Hard Choices with Felbamate. Washington University School of Medicine. (April 23, 2004). “Felbamate (Systemic).” Medline Plus. National Library of Medicine. (April 23, 2004). ORGANIZATIONS

American Epilepsy Society. 342 North Main Street, West Hartford, CT 06117-2507, USA. . Epilepsy Foundation. 4351 Garden City Drive, Landover, MD 20785-7223. (800) 332-1000. .

Adrienne Wilmoth Lerner

❙ Fisher syndrome Definition

Fisher syndrome is a rare, acute neurological disorder characterized by a triad of clinical manifestations that includes brain-damage associated abnormal coordination (ataxia), a condition that involves the paralysis of the eyes called ophthalmoplegia, and a generalized absence of reflexes (areflexia).

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Fisher syndrome

Description Fisher syndrome is also known as Miller Fisher syndrome, as was described in 1956 by Canadian physician Charles Miller Fisher. It is an acute, rare nerve disease that is considered to be a variant of Guillain-Barré syndrome. In both syndromes, the associated nerve disease can be acquired after viral illness. Once the disorder is diagnosed and treated, the physical and mental effects can be minimal or absent, thus emphasizing the importance of medically identifying affected individuals and treating them accordingly. Fisher syndrome is also known as acute idiopathic ophthalmologic neuropathy syndrome of ophthalmoplegia, ataxia, and areflexia. Related conditions include disorders called Bickerstaff’s brainstem encephalopathy and acute ophthalmoparesis.

Demographics Fisher syndrome is an extremely rare disorder. It is reported to affect persons between the ages of 38 and 65 years old. The related Guillain-Barré syndrome is more common than Fisher syndrome. Age is not a factor, and anyone who produces specific antibodies can acquire it.

Causes and symptoms The majority of affected individuals with Fisher syndrome produce an antibody by their immune system that is related to the susceptibility to develop the disease following a viral illness; it is unclear how. It is thought that the antibody anti-GQ1b IgG is associated with paralysis of the eye, or ophthalmoplegia. The cause of Fisher syndrome and Guillain-Barré syndrome in both cases is due to an autoimmune disease whereby antibodies produced by the body’s immune system mistakenly attack a nerve insulator and impulse carrier called the myelin sheath. This causes inflammation and damage to the nervous system. GuillainBarré syndrome differs from Fisher syndrome in that different nerve groups are targeted and paralysis in the former begins with the legs and moves upward. Fisher syndrome, on the other hand, begins in the head (paralysis of the eyes) and moves in the direction toward the neck and arms. Although the direct cause is unknown, 65% of cases are thought to be linked to herpes-related viral illness (although viruses other than herpes can also be involved). The first symptoms appear to be related to a virus and include a headache, fever, and pneumonia. The characteristic triad of symptoms that result in individuals who acquire Fisher syndrome is in addition to generalized muscle atrophy (weakness) and respiratory complications that can involve respiratory failure if untreated. It is uncommon to observe a patient with Fisher syndrome that does not have some degree of generalized weakness. Damage to motor 370

function is believed to be associated with damage sustained by the cranial nerves of the brain, with sensory nerve damage extending to the patient’s arms and legs. In cases that also include abnormalities in the brainstem, it is more likely to be due to a related disorder called Bickerstaff’s syndrome.

Diagnosis Diagnosis is made clinically by detecting manifestations involving the characteristic trio of symptoms usually following a viral infection: paralysis of the eyes (ophthalmoplegia), abnormal coordination (ataxia), and absence of reflexes (areflexia).

Treatment team Patients are usually treated by a physician that specializes in infectious diseases, and a neurologist. Diagnosis and treatment are usually made by these professionals.

Treatment Treatment for Fisher syndrome involves removing the plasma from affected individuals, a procedure called plasmapheresis. In doing so, antibodies that cause the disease are also removed. In the alternative, patients can be treated with an intravenous injection of immunoglobulin (IVIg) to boost the immune system. Untreated patients can experience double vision, nausea, difficulty walking, and sensitivity to light that can continue for several months.

Recovery and rehabilitation Once Fisher syndrome is identified, treatment can lead to recovery in as soon as two to four weeks after the symptoms are initially acquired. After six months, the symptoms are usually almost completely resolved. Although some individuals have secondary complications and relapses occur in 3% of cases, most individuals have a nearly complete recovery.

Clinical trials As most affected individuals who are treated have a good prognosis, clinical trials to treat the disorder are not currently being investigated. There is research being conducted to find better ways to diagnose and ultimately cure the neurological damage that sometimes occurs in Fisher syndrome.

Prognosis The prognosis is good for individuals who are detected and treated soon after the onset of symptoms. In these cases, affected individuals have a favorable prognosis and (on average) should expect to have a normal lifespan. This disorder is seldom life-threatening.

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Areflexia Absence of a reflex; a sign of possible nerve damage. Ataxia Loss of coordinated movement caused by disease of nervous system. Ophthalmoplegia Paralysis of the motor nerves of the eye.

Resources BOOKS

Staff. The Official Patient’s Sourcebook on Miller Fisher Syndrome: A Revised and Updated Directory for the Internet Age. San Diego: Icon Group International, 2002.

Demographics Foot drop affects both males and females. However, it is more common in males (the male to female ratio is approximately 2.8:1). Both feet are equally as prone to develop the problem. Some forms of foot drop occur in mid-aged people who put stress on that area of the body during athletics. Surgery to the knee or leg can lead to nerve damage that then leads to the development of foot drop. For example, approximately 0.3–4% of people who have a surgical procedure called a total knee arthroplasty develop foot drop. People who undergo surgery to the tibia (a leg bone) subsequently experience foot drop at a rate of 3–13%.

Causes and symptoms

PERIODICALS

Derakhshan, I. “Recurrent Miller Fisher Syndrome.” Neurol India. (June 2003): 283. OTHER

NINDS Miller Fisher Syndrome Information Page. National Institute of Neurological Disorders and Stroke. March 4, 2004 (May 22, 2004). . ORGANIZATIONS

Guillain-Barré Syndrome Foundation International. P.O. Box 262, Wynnewood, PA 19096. (610) 667-0131; Fax: (610) 667-7036. [email protected]. .

Bryan Richard Cobb, PhD

Floppy infant syndrome see Hypotonia

❙ Foot drop Definition

Foot drop is a weakness of muscles that are involved in flexing the ankle and toes. As a result, the toes droop downward and impede the normal walking motion.

Description The use of the term foot drop can make it seem as if the condition is rather simple and inconsequential. This is not the case. Foot drop can be a consequence of injury to muscles that are known as dorsiflexor muscles, injury to certain nerves, a stroke, brain injury, toxic effect of drugs, and even diabetes. Foot drop is likely not a new malady. Historical descriptions that match foot drop date back over 2000 years.

Foot drop is caused by weakness that occurs in specific muscles of the ankle and the foot. The affected muscles participate in the downward and upward movement of the ankle and the foot. The specific muscles include the anterior tibialis, extensor hallucis longus, and the extensor digitorum longus. The normal function of these muscles is to allow the toes to swing up from the ground during the beginning of a stride and to control the movement of the foot following the planting of the heel towards the end of the stride. Abnormal muscle function makes it difficult to prevent the toes from clearing the ground during the stride. Some people with foot drop walk with a very exaggerated swinging hip motion to help prevent the toes from catching on the ground. Another symptom of foot drop, which occurs as the foot is planted, is an uncontrolled slapping of the foot on the ground. There are three general causes of the muscle weakness. Damage to nerves can affect the transmission of impulses that help control muscle movement and function. Motor neuron diseases such as amyotrophic lateral sclerosis (ALS) or post-polio syndrome, tumors in the brain or spinal cord, or diseases of the nerve roots of the lumbar spine are all neurological conditions that may produce foot drop. Second, the muscles themselves may be damaged. Third, there can be some skeletal or other anatomical abnormality that affects the movement of the ankle or foot. A combination of these factors can also be involved, as is the case with the drop foot malady known as Charcot foot.

Diagnosis Diagnosis of foot drop is based on the visual appearance of the altered behavior of the foot. Analysis of blood can be done to look for a metabolic cause, such as diabetes, alcoholism, or presence of a toxin. Among the tests

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Foot drop

Key Terms

Foot drop can also be described as drop foot, steppage gait, and as equinovarus deformity.

Fourth nerve palsy

and Stroke supports research into many of the neurological conditions that may result in foot drop.

Key Terms Gait Body position during and manner of walking. Orthotic A device applied to or around the body to aid in positioning or mobility, commonly used to control foot mechanics.

commonly performed are fasting blood sugar, hemoglobin determination, and determination of the levels of nitrogen and creatinine. Visual examination of the foot can include routine photographs, magnetic resonance imaging or magnetic resonance neurography (both of which are useful in visualizing areas surrounding damaged nerves). An electromyelogram can be useful in distinguishing between the different types of nerve damage that can be responsible for foot drop.

Treatment team Treatment can involve the family physician, family members, and physical therapists. Physical therapists guide exercises that assist in maximizing muscular strength.

Prognosis When foot drop is due to a compressed nerve, corrective surgery can produce a complete recovery within several months. If the cause is a skeletal problem or other neurological problem, the prognosis for complete recovery is not as certain. Resources BOOKS

Ronthal, Michael. Gait Disorders. Boston: ButterworthHeinemann, 2002. OTHER

“Foot Drop.” eMedicine.com. (May 5, 2004).

“Peroneal Neuropathy” drkoop.com. (May 1, 2004).

ORGANIZATIONS

National Institute of Arthritis and Musculoskeletal and Skin Diseases (NIAMS) National Institutes of Health. Bldg. 31, Rm. 4C05, Bethesda, MD 20892. (301) 496–8188; Fax: (540) 862–9485. [email protected]. .

Brian Douglas Hoyle, PhD

Treatment Foot drop that cannot be treated by surgery is often treated using a special orthotic device that provides normal range of motion to the foot and ankle during walking. Other people with foot drop can benefit from the stimulation of the affected nerves. The stimulation is applied as the foot is raised during a stride and is stopped when the foot touches down on the ground. When the cause of foot drop is a muscular or nerve difficulty, surgery can be beneficial. Surgery can relieve the pressure on a compacted nerve, repair a muscle, and even restore a normal gait by lengthening the Achilles tendon or replacing a defective tendon.

Recovery and rehabilitation

Definition

The sole function of the fourth nerve is innervation of the superior oblique muscle, which is one of the six muscles of eye movement. Fourth nerve palsy or trochlear nerve palsy is a neurological defect resulting from dysfunction of the fourth cranial nerve. Double vision, also known as diplopia, may occur because of the inability of the eyes to maintain proper alignment.

Description

Depending on the nature of the cause of foot drop, recovery can be partial or complete. Physical therapy and an ankle foot orthotic device worn in the shoe are important aspects of rehabilitation.

Clinical trials As of mid-2004, there were no clinical trials recruiting participants for the study or treatment of foot drop, although the National Institute of Neurological Disorders 372

❙ Fourth nerve palsy

Trochlear nerve palsy has been described since the mid-1800s. Bielchowsky was first to describe it as the leading cause of vertical (two images appearing one on top of the other or at angles) double vision. Injury to the fourth cranial nerve can stem from congenital or acquired causes with one or both nerves being affected. It is unclear whether the congenital variant of this disorder is due to developmental abnormalities of the nerve itself or nucleus, which is an area of the brain where

GALE ENCYCLOPEDIA OF NEUROLOGICAL DISORDERS

Demographics Fourth nerve palsies have no predilection for males or females. It is difficult to accurately predict the occurrence of congenital palsies since some go unnoticed throughout a person’s life. Acquired nerve palsies are more likely to occur in older patients with diabetes or vascular disease versus the general population.

Key Terms Diplopia Visual sensation of seeing two images of the same object, resulting from a failure of the eyes to properly align. Also known as double vision. Superior oblique muscle One of six extraocular muscles concerned with eye movement. The superior oblique muscle pushes the eye down, turns it inward and rotates it outward. Myasthenia gravis An autoimmune disease characterized by fluctuating weakness of voluntary muscles from antibodies which block neurochemical transmission at the neuromuscular junction.

Causes and symptoms Causes of fourth nerve palsy can be broadly classified as congenital or acquired. Isolated congenital palsies may be heralded by head-tilting to the opposite side of the affected nerve in early childhood. In others a congenital palsy may go unnoticed because of a compensatory mechanism allowing for alignment of the eyes when focusing on an image. Isolated acquired trochlear nerve palsies can be the result of numerous disorders. Most commonly an underlying cause cannot be found and this is known as an idiopathic palsy. Due to its long course within the brain, the fourth nerve is susceptible to injury following severe head trauma. Depending on the site of nerve compression during trauma one or both nerves may be affected. Aneurysms or brain tumors may directly compress or result in an increase of intracranial pressure (the pressure within the skull) resulting in nerve palsies. Disorders such as myasthenia gravis, diabetes, meningitis, microvascular disease (atherosclerotic vascular disease) or any cause of increased intracranial pressure may result in trochlear nerve palsy. A congenital palsy that has gone undetected may manifest itself in adulthood when the compensatory mechanism for ocular alignment is lost. Additionally the removal of a cataract may restore clear vision to both eyes allowing the patient to become aware of their double vision. A child with a congenital palsy may be found doing a head tilt by his or her parents or relatives. Children will very rarely complain of double vision. Adults with a new onset fourth nerve palsy will note two images, one on top of the other or angled in position when both eyes are open. Covering of one eye, no matter which one is covered, will resolve their diplopia. Their double vision will worsen when looking down or away from the affected side. If both nerves are affected he or she may experience a horizontal diplopia (two images side by

side) when looking downward. If a decompensated palsy is suspected, one should review old photographs to document a pre-existing head tilt to support the diagnosis.

Diagnosis Diagnosing a fourth nerve palsy is for the most part a clinical diagnosis. Careful history taking and examination is the key to diagnosis. The Bielchowsky head-tilt test is one commonly used and reliable technique to diagnose isolated trochlear nerve palsies. Review of patient’s old photographs can prove indispensable in diagnosing a decompensated palsy, obviating the need for additional testing. Computed tomography or magnetic resonance imaging may be needed if the palsy is thought to be due to a structural brain lesion. Blood work or a lumbar puncture may be ordered if myasthenia gravis, meningitis or other systemic disorders are considered as potential causes.

Treatment team Ophthalmologists, neuro-ophthalmologists, optometrists and neurologists are medical specialists who can evaluate and diagnose a patient with a fourth nerve palsy. Usually an optometrist or ophthalmologist will initially see a patient complaining of diplopia or displaying stigmata of trochlear nerve palsy. A referral will then likely be made to a neurologist or neuro-ophthalmologist for evaluation and workup.

Treatment Since most fourth nerve palsies are idiopathic, treatment is conservative given the high rate of spontaneous resolution. Monitoring a patient for six months to one

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the nerve begins and receives signals for proper functioning. In addition the muscle and its tendon may also display abnormal laxity and muscle fiber weakness. Most cases of acquired fourth nerve palsy results from dysfunction of the nerve itself, although cerebrovascular accidents (stroke) may directly injure the nucleus.

Friedreich ataxia

year for improvement can prove to be frustrating and disabling for the patient. A prism may resolve or greatly reduce a patient’s diplopia during this period, allowing for return to normal daily activities, such as driving, shopping or reading. Botulinum toxin used to weaken muscles that overact, causing ocular misalignment, in the presence of a trochlear nerve palsy has been disappointing thus far. Surgery aimed at weakening or strengthening one or more of the extraocular muscles has proven useful in many cases of persistent palsies. Indications for surgery include worsening diplopia, head-tilt resulting in neck pain and poor cosmetic appearance. Procedures performed include the Knapp, Plager or Harada-Ito techniques and are chosen based on the amount and type of ocular misalignment found on examination. These procedures weaken or strengthen extraocular muscles by relocating their attachments to the eye. Muscles may also be weakened by cutting across or removing a portion of the muscle.

Resources BOOKS

Burde, Ronald M., Peter J. Savino, and Jonathan D. Trobe. Clinical Decisions in Neuro-Ophthalmology, 3rd ed. St. Louis: Mosby, 2002. Liu, Grant T., Nicholas J. Volpe, and Steven L. Galetta. NeuroOphthalmology Diagnosis and Management, 1st ed. Philadelphia: W. B. Saunders Company, 2001. Neuro-Ophthalmologic and Cranial Nerve Disorders; Section 14, Chapter 178. The Merck Manual of Diagnosis and Therapy, edited by Mark H. Beers and Robert Berkow. Whitehouse Station, NJ: Merck Research Laboratories, 1999. Newman, Nancy J., ed. Ophthamology Clinics of North America, pp. 176-179. Philadelphia: W. B. Saunders Company, 2001. PERIODICALS

Brazis, Paul W. “Palsies of the trochlear nerve: diagnosis and localization-recent concepts.” Mayo Clinic Proceedings 68, no. 5 (May 1993): 501. WEBSITES

Sheik, Zafar A., and Kelly A. Hutcheson. “Trochlear Nerve Palsy.” eMedicine.com. .

Recovery and rehabilitation A six-month to one-year waiting period is warranted to observe for spontaneous improvement. During this period the patient may benefit from prismatic lenses to eliminate or reduce their diplopia. Eye movement exercises have not proved useful for improving or expediting recovery.

❙ Friedreich ataxia Definition

Clinical trials As of November, 2003 no clinical trials regarding trochlear nerve palsies were underway.

Prognosis The prognosis for trochlear nerve palsies is dependent upon the underlying cause. Most cases of idiopathic or microvascular nerve palsies resolve within a several weeks to six-month time period without treatment. Traumatic nerve palsies may take up to one year to resolve, with less than half regaining any improvement. Palsies secondary to brain masses or aneurysms have the least likelihood of any recovery and may take up to one year to improve. If present, proper treatment of myasthenia gravis or other underlying systemic disease, excluding a cerebrovascular accident usually results in complete recovery in the vast majority of cases.

Special concerns Patients afflicted with a fourth nerve palsy should refrain from driving unless an eye patch is used. In addition certain types of employment may warrant a medical leave or temporary change of duties. 374

Adam J. Cohen, MD

Friedreich ataxia (FRDA or FA) is an inherited, degenerative nervous system disorder that results in muscle weakness and inability to coordinate voluntary muscle movements.

Description Onset of FDRA is usually in childhood or early adolescence. The disorder is characterized by unsteady gait, slurred speech, absent knee and ankle jerks, Babinski responses, loss of position and vibrations senses, leg muscle weakness, loss of leg muscle mass, scoliosis, foot deformities, and heart disease. FRDA is a slowly progressive condition associated with a shortened life span, most often due to complications of heart disease. FRDA is named for Nikolaus Friedreich, the German doctor who first described the condition in 1863. The most common form of the disorder, found in about three–quarters of patients, is referred to as “classic” or “typical” FDRA. Atypical forms of FDRA include: late onset Friedreich ataxia (LOFA), very late onset Friedreich ataxia (VLOFA), Friedreich ataxia with retained reflexes (FARR), Acadian type (Louisiana form), and spastic paraparesis without ataxia.

GALE ENCYCLOPEDIA OF NEUROLOGICAL DISORDERS

2 24 23 22 21 1

p q

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1

CDKN2: Malignant melanoma

FRDA: Friedreich’s ataxia

13 21

2 22 Familial dysautonomia

3

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OWR1: Olser-Weber-Rendu syndrome

34

Distal arthrogryposis syndrome (9)

Friedreich ataxia, on chromosome 9. (Gale Group.)

Demographics FRDA is the most common inherited ataxia and affects between 3,000–5,000 people in the United States. The prevalence of FDRA in the Caucasian population is approximately one in 50,000 to one in 25,000. Prevalence appears to be highest in French Canadians from Quebec, Acadians from Louisiana, and among certain populations in southern Italy and Cyprus. Approximately 1% of Caucasian individuals carry one defective copy of the gene responsible for FRDA, known as FRDA1. FRDA is rare in people of Asian or African descent.

Causes and symptoms FRDA is an autosomal recessive condition, which means that an affected individual has two altered or nonfunctioning FRDA1 genes, one from each parent. The FRDA1 gene is located on chromosome 9 and codes for a protein called frataxin. The most common gene alteration (or mutation), which is found in greater than 95% of affected individuals, is a triplet repeat expansion. The triplet repeat is a sequence of DNA bases called GAA. Normally the GAA sequence is repeated five to 33 times but in people with FRDA, it is repeated between 66 to 1700 times. Longer GAA triplet repeats are associated with more severe disease, but the severity of disease in a given individual cannot be predicted from the repeat length. About

4% of patients have the triplet repeat expansion in one copy of the FDRA1 gene and a different type of mutation, a point mutation, in the other FRDA1 gene. There have been a few patients with classic FDRA in which the FRDA1 gene on chromosome 9 has been shown not to be the cause. FRDA1 gene mutations lead to loss of function of the gene and subsequently to decreased production of frataxin. Frataxin plays a role in the balance of iron in the mitochondria, the cellular energy structures. Frataxin insufficiency leads to a number of effects including excessive iron accumulation in the mitochondria and, eventually, the production of chemicals called free radicals that can damage and kill the cell. The cells most affected in FRDA are those in the brain, spinal cord, nerves, heart, and pancreas. FRDA is a slowly progressive, unremitting, ataxia. There is variability in age of onset, presence of symptoms, rate of progression, and severity. Although onset of FRDA usually occurs before age 25, symptoms may appear as early as age two or as late as 30 to 40 years. Gait ataxia, or difficulty walking, is often the first sign of the disease. For example, an affected child might trip frequently over low obstacles. The ataxia eventually spreads to the arms within several years, resulting in decreased hand-eye coordination. Unsteadiness when standing still and deterioration of position sense is common. Other symptoms that appear early in the course of the disease are loss of knee and ankle tendon reflexes and dysarthria (slowness and slurring of speech). Over time, individuals with FRDA experience loss of sensation that begins in their hands and feet and may spread to other parts of the body. Abnormal muscle control and tone leads to problems such as scoliosis (curvature of the spine) and foot deformities such as pes cavus (high-arched feet) with extensor plantar response. Arm weakness, if it occurs, develops later in the course of the disorder. Loss of muscle control eventually necessitates use a wheelchair. Heart disease represents a potentially significant complication of FRDA. Heart muscle enlargement with or without an abnormal heartbeat is present in about two–thirds of cases and represents a major cause of death. About one–third of patients develop diabetes, most of whom will require insulin. Other medical findings in FRDA include optic nerve atrophy, nystagmus (eye tremor), tremor, amyotrophy (loss of muscle mass), hearing loss, difficulty swallowing, and incontinence.

Diagnosis A diagnosis of FDRA is based on clinical findings and results of genetic testing. The clinical diagnosis of Friedreich ataxia is made through physical exam and medical history. The presence of progressive ataxia, loss of position and/or vibration sense, and loss of lower limb

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Chromosome 9

Friedreich ataxia

Key Terms Amniocentesis A procedure performed at 16-18 weeks of pregnancy in which a needle is inserted through a woman’s abdomen into her uterus to draw out a small sample of the amniotic fluid from around the baby for analysis. Either the fluid itself or cells from the fluid can be used for a variety of tests to obtain information about genetic disorders and other medical conditions in the fetus. Chorionic villus sampling (CVS) A procedure used for prenatal diagnosis at 10–12 weeks gestation. Under ultrasound guidance a needle is inserted either through the mother’s vagina or abdominal wall to draw out a sample of the chorionic membrane. These cells are then tested for chromosome abnormalities or other genetic diseases.

consisting of a complex of proteins and DNA. Humans have 46 chromosomes arranged into 23 pairs. Chromosomes contain the genetic information necessary to direct the development and functioning of all cells and systems in the body. They pass on hereditary traits from parents to child (like eye color) and determine whether the child will be male or female. DNA Deoxyribonucleic acid; the genetic material in cells that holds the inherited instructions for growth, development, and cellular functioning.

Chromosome A microscopic thread-like structure found within each cell of the human body and

Gene A building block of inheritance, which contains the instructions for the production of a particular protein, and is made up of a molecular sequence found on a section of DNA. Each gene is found on a precise location on a chromosome.

tendon reflexes in a child or adolescent is suspicious of the diagnosis. Tests that may aid in diagnosis include electromyography, nerve conduction studies, an electrocardiogram, an echocardiogram, magnetic resonance imaging (MRI), computed tomography (CT) scan, a spinal tap, and glucose analysis of blood and urine. Genetic testing is recommended for all individuals in whom the diagnosis of FRDA is suspected.

with FRDA may receive comprehensive services through a muscular dystrophy association (MDA) clinic and/or a Shriner’s Hospital for Children. A genetic specialist, such as a clinical geneticist or a genetic counselor, may be helpful to the patient and family, especially at the time of diagnosis or prior to genetic testing. Psychological counseling and support groups may also assist families in coping with this condition.

Genetic testing is accomplished by counting the number of GAA repeats in the FRDA gene to see if there is an expansion (66 or more repeats). For those cases in which only one FRDA gene has a triplet repeat expansion, the same genetic test may be used to determine the presence of the genetic defect in the carrier state (i.e., one normal copy and one defective copy of the frataxin gene) in unaffected individuals, such as adult siblings, who would like to learn their chances of producing an affected child. During pregnancy, the DNA of a fetus can be tested using cells obtained from chorionic villus sampling (CVS) or amniocentesis.

Treatment team Management of FRDA requires a multidisciplinary approach. In addition to the patient’s primary health care professionals, medical professionals involved in the care of patients with FRDA generally include a neurologist, a cardiologist, an orthopedic surgeon, an ophthalmologist, a speech therapist, a physical therapist, an occupational therapist, and a physiatrist. Additional specialists in endocrinology and urology may be needed. Some patients 376

Treatment As of 2003, there is no cure for FRDA. The purpose of treatment, which is largely supportive, is to help patients optimize function and to manage any associated medical complications of the disorder. Treatment includes most if not all of the following options: • Orthopedic intervention. Braces or surgery may be necessary to treat scoliosis and foot deformities. For example, a surgical procedure known as spinal fusion may be considered in patients with significant curvature. • Medications. Some antioxidants (chemicals that capture free radicals) have shown benefits in patients with FRDA. Vitamin E and coenzyme Q10, which are naturally occurring substances, may be prescribed. Patients should discuss the current recommendations with their physician. • Cardiac and diabetes care. Since cardiac disease is the most common cause of death, proper cardiac care is essential. For those cases in which there is heart disease,

GALE ENCYCLOPEDIA OF NEUROLOGICAL DISORDERS

Recovery and rehabilitation Rehabilitation for Friedreich ataxia consists of speech, physical, and occupational therapy. The goal of these therapies is to make full use of the patient’s existing muscular functions. For example, physical therapy can help stretch muscles to improve or maintain flexibility. Speech therapy can help to retrain certain muscles in order to improve speech and swallowing. Occupational therapy can teach patients to use adaptive techniques and devices that may help compensate for loss of coordination and strength. For example, prostheses, walking aids, and wheelchairs may be recommended to help the individual with FRDA to remain ambulatory or mobile.

Clinical trials Research studies of idebenone, a synthetic antioxidant, have shown it to reduce hypertrophy (overgrowth) of the left ventricle of the heart in patients with FRDA. A phase I clinical trial will be conducted in the United States to establish the maximum tolerated dose of idebenone in children, adolescents, and adults with Friedreich’s ataxia; as of November 2003, active patient recruitment was underway. Information on this trial can be found at or by contacting the National Institute of Neurological Disorders and Stroke patient recruitment and public liason office at 1-800-4111222. Another substance that is being researched is an antioxidant known as mitoquinone or “MitoQ” which is a synthetic form of coenzyme Q10 that has the potential to protect the mitochondria from free radical damage. As of 2003, mitoquinone was in the developmental phase of study and not yet available to patients.

Prognosis The rate of progression of FRDA varies. Most patients lose the ability to walk within 15 years of symptom onset, and 95% require a wheelchair for mobility by age 45. Shortened life span from FRDA complications, usually cardiac, is also quite variable. Average age at death, usually from heart problems, is in the mid-30s, but may be as late as the mid-60s.

Special concerns A child with a diagnosis of Friedreich ataxia is eligible to have an Individual Education Plan (IEP). An IEP provides a framework from which administrators, teachers, and parents can meet the educational needs of a child with FRDA. Resources BOOKS

Nance, Martha A. Living with Ataxia, 2nd ed. Minneapolis: National Ataxia Foundation, 1997. Parker, James N., and Philip M. Parker, eds. The Official Parent’s Sourcebook on Friedreich’s Ataxia: A Revised and Updated Directory for the Internet Age. San Diego, CA: ICON Health Publications, 2002. Ruzicka, Evzen, Mark Hallett, and Joseph Jankovic, eds. Gait Disorders. Philadelphia, PA: Lippincott Williams and Wilkins, 2001. PERIODICALS

Alper, G., and V. Narayanan. “Friedreich’s Ataxia.” Pediatric Neurology 28 (May 2003): 335–341. Pilch, J., E. Jamroz, and E. Marza. “Friedreich’s Ataxia.” Journal of Child Neurology 17 (May 2002): 315–319. WEBSITES

Friedreich’s Ataxia Parents Group (FAPG). . The Muscular Dystrophy Association (MDA). Facts about Friedreich’s Ataxia (FA). . The National Institute of Neurological Disorders and Stroke (NINDS). Friedreich’s Ataxia Fact Sheet. . ORGANIZATIONS

Friedreich’s Ataxia Research Alliance (FARA). 2001 Jefferson Davis Highway, Suite 209, Arlington, VA 22202. (703) 413-4468; Fax: (703) 413-4467. [email protected]. . Muscular Dystrophy Association. 3300 East Sunrise Drive, Tucson, AZ 85718. (520) 529-2000 or (800) 572-1717; Fax: (520) 529-5300. [email protected]. . National Ataxia Foundation (NAF). 2600 Fernbrook Lane, Suite 119, Minneapolis, MN 55447. (763) 553-0020; Fax: (763) 553-0167. [email protected]. .

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Dawn J. Cardeiro, MS, CGC

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medications can be effective for many years. Of those individuals with diabetes mellitus, most will require insulin therapy.

G ❙ Gabapentin Definition

Gabapentin is a prescription drug that was initially approved to help manage epilepsy. The Food and Drug Administration (FDA) has also approved gabapentin for treatment of the nerve pain that sometimes accompanies herpes infections. Gabapentin is available in the United States under the trade name Neurontin.

Purpose Although the FDA has only approved gabapentin for managing epilepsy and treating nerve pain associated with herpes infections, doctors often prescribe the medication for managing other conditions, including tremors associated with multiple sclerosis, nerve pain, bipolar disorder, and migraine prevention.

involved in pain conduction. This may account for the drug’s ability to alleviate pain, especially nerve pain. When gabapentin is used along with other therapies for managing epileptic partial seizures, improvements should be observed within 12 weeks. On the other hand, pain relief may be evident within one week when the drug is used for pain associated with herpes infections.

Recommended dosage For adults, the initial dose of gabapentin is 300 mg taken by mouth three times each day. The dosage may be increased if necessary. Dosages as high as 800–1,200 mg three times daily have been well tolerated. In children three to 12 years of age, the starting dose should be 10–15 mg/2.2 lb (1 kg)/day given in three equal doses. This dose can be increased until an effective dosage is reached, typically 25–40 mg/2.2 lb (1 kg)/day. Lower dosages are required for patients that have kidney disease.

Description As an antiepileptic drug, gabapentin may be used in conjunction with other drugs to prevent partial seizures. Partial seizures are caused by brief abnormal electrical activity in localized areas of the brain. Partial seizures usually do not cause unconsciousness, but may cause rhythmic contractions in one area of the body or abnormal numbness or tingling sensations. Although gabapentin was originally approved by the FDA in 1993, it is still not understood how gabapentin prevents seizures. However, the drug is related to gammaaminobutyric acid (GABA), a neurochemical that possesses inhibitory properties. In brain cells, these inhibitory actions prevent excitatory electrical impulses from spreading to neighboring cells. As a result, gabapentin probably prevents the spread of abnormal excitatory activity in the brain at least in part, by mimicking the actions of GABA. By preventing excitatory communication between cells, gabapentin may also inhibit the electrical impulses

Precautions In children, gabapentin may cause behavioral and emotional disorders. The drug should be used cautiously and the dosage should be reduced in those with severe kidney disease. In experimental animals, gabapentin caused tumors to develop; however, it is not known if this occurs in humans. Patients should take gabapentin only as prescribed. The drug should never be stopped abruptly because doing so increases the likelihood of having a seizure. Since gabapentin can cause dizziness and fatigue, patients should avoid driving or operating complex machinery until they know whether the drug adversely affects their reaction time or impairs their judgment.

Side effects The most common side effects that cause adults to stop taking gabapentin are dizziness, sleepiness, fatigue, shaky movements, difficulty walking, or swelling in the ankles.

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Gaucher disease

Key Terms Antiepileptic A drug that prevents or limits the spread of epileptic seizures. Bipolar disorder A mental illness that causes episodes of depression and mania; also known as manic-depressive illness.

Migraine A recurrent headache, often accompanied by vomiting, that typically affects just one side of the head. Milligram (mg) One-thousandth of a gram, or about the equivalent of 0.035 ounces (oz).

Epilepsy A chronic nervous system disorder that typically causes temporary behavior changes, uncontrolled shaking, loss of attention, or unconsciousness.

Multiple sclerosis A chronic disease of the central nervous system in which the tissues surrounding the brain and spinal cord are damaged.

Gamma-aminobutyric acid (GABA) The major inhibitory neurotransmitter in the brain.

Neurotransmitter A chemical in the brain that transmits messages between neurons or nerve cells.

Herpes A virus that causes cold sores, sexually transmitted diseases, shingles, or chicken pox.

Partial seizures Brief, temporary alterations in movement or sensory nerve function cause by abnormal electrical activities in localized regions of the brain.

Kilogram (kg) One thousand grams, or about the equivalent of 2.2 pounds (lb).

In children, the side effects the drug may cause include emotional problems, hostility, and hyperactivity.

Interactions Unlike many other drugs that are used to treat epilepsy, there are few drug interactions associated with gabapentin. It is recommended, however, that antacids not be used sooner than two hours after gabapentin to avoid compromising gabapentin’s effectiveness. Resources BOOKS

Drug Facts and Comparisons, 6th edition. St. Louis, MO: A Wolter Kluwer Company, 2002. Mosby’s Medical Drug Reference. St. Louis, MO: Mosby, Inc, 1999. Neurontin Package Insert. Vega Baja, PR: Parke-Davis Pharmaceuticals, Ltd., 2002.

Kelly Karpa, PhD, RPh

Gaucher disease belongs to a group of conditions called lipid storage diseases. Lipids are fatty substances used throughout the body. In lipid storage diseases, enzymes that would ordinarily break down lipids so that they can be appropriately used are absent. This results in the progressive accumulation of large quantities of these lipids. In Gaucher disease, the specific type of lipid that accumulates is called a glucosylceramide. Deficient activity of an enzyme called beta-glucosidase results in glucosylceramide accumulation throughout the body and damage to normal tissues and organs. There are three types of Gaucher disease. Type 1 is the most common. Each type has a characteristic age of onset and constellation of symptoms.

Demographics In the general population, one in 50,000–100,000 develop Gaucher disease. However, Gaucher type 1 disease is considerably more common among Jewish people from eastern and central Europe (Ashkenazi Jews), affecting one in 500–1,000 individuals.

Galantamine see Cholinesterase inhibitors

❙ Gaucher disease

Causes and symptoms

Definition

Gaucher disease is a rare, inherited disorder in which a deficient or missing enzyme causes an abnormal buildup of a fatty substance called glucosylceramide throughout the body. Abnormal accumulations of this substance are toxic to organs and tissues, resulting in progressive, permanent damage. 380

Description

Gaucher disease is an inherited disease, caused by a defective GBA gene. The disease is recessive, meaning that a child has to inherit a defective gene from both the mother and the father in order to have the actual condition. Type 1 affects both children and adults. Its major manifestations include easy bruising, anemia, fatigue,

GALE ENCYCLOPEDIA OF NEUROLOGICAL DISORDERS

Type 3 causes the same kinds of symptoms seen in type 2, but the neurological involvement is more mild and the progression is more gradual.

36 35

Diagnosis

34 3

Diagnosis of Gaucher disease can be made by performing a bone marrow examination, and identifying specific “Gaucher cells” within the specimen. Other cells can be examined to demonstrate decreased activity of the enzyme beta-glucosidase. DNA testing can also reveal the specific mutation responsible for the disease, particularly within Ashkenazi Jewish populations.

33 32 31

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Marshall syndrome

Treatment team

13 1

p q

12 11 11

1 12 GBA: Gaucher disease 21

PKLR: Pyruvate kinase deficiency

22 2 23

Factor V deficiency HPC1: Prostate cancer

The treatment team may vary, depending on the patient’s specific symptoms. Early in the diagnostic phase, a geneticist may be helpful. If neurological problems predominate, a neurologist will be necessary. A hematologist may be consulted to handle the blood-related complications such as anemia. Other specialists may include an ophthalmologist, orthopedic surgeon, physical and occupational therapists, and speech and language therapist.

24 25

GLC1A: Glaucoma

31 3 PS2(AD4): Alzheimer’s disease 32

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CHS1: Chediak-Higashi syndrome

43 44

Treatment Symptomatic treatment may include blood transfusions to treat anemia, removal of the enlarged spleen, and joint replacement. Some patients have been cured via bone marrow transplant, but this procedure carries a very high risk of complications and death, and requires a carefully matched donor, which can be difficult to find. Newer treatments include enzyme replacement therapy. While not curative, intravenous enzyme replacement can decrease the severity of, or reverse, many of the complications of type 1 disease, including liver/spleen enlargement, anemia, neurologic problems, and bone abnormalities. Severe brain damage cannot be reversed, however.

Gaucher disease, on chromosome 1. (Gale Group.)

liver and/or spleen enlargement, bone and joint pain, joint problems, and increased risk of bone fractures. Type 2 usually begins to show symptoms during infancy. This type causes many of the same symptoms seen in type 1 (easy bruising, anemia, liver and/or spleen enlargement), but it also results in severe and progressive neurological problems. Damage to the central nervous system results in seizures, difficulty walking, paralyzed

Clinical trials A variety of clinical trials on Gaucher disease are being conducted, including testing of a medicine called OGT918 that may slow or decrease the accumulation of lipids, hopefully with improved neurological outcomes. Other clinical trials are evaluating the outcome of treatment with enzyme replacement therapy in Gaucher disease types 2 and 3, the effect of alendronate sodium on bone disease in Gaucher disease, and the short- and longer-term outcome of bone marrow or umbilical cord blood transplantation in children with Gaucher disease.

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eye muscles, and progressive dementia. Most patients with type 2 disease die by about age two.

Chromosome 1

Gene therapy

Key Terms Beta-glucosidase An enzyme responsible for breaking down glucosylceramide. Glucosylceramide A chemical substance composed of glucose (sugar) and lipid (fat).

Children’s Gaucher Research Fund. PO Box 2123, Granite Bay, CA 95746. (916) 797-3700; Fax: (916) 797-3707. [email protected]. . National Gaucher Foundation. 5410 Edson Lane, Suite 260, Rockville, MD 20852-3130. (301) 816-1515 or 800GAUCHER (428-2437); Fax: (301) 816-1516. ngf@ gaucherdisease.org. .

Lipid A fatty substance in use throughout the body.

Rosalyn Carson-DeWitt, MD

Prognosis The prognosis of Gaucher disease depends on the specific type. Because type 1 has no neurologic manifestations, it has the best prognosis. Lifespan depends on the severity of the complications, but some patients live into the 70s or 80s. Type 2 is universally fatal, generally by about age two. Patients with type 3 generally survive until about age 20 or 30.

Special concerns Carriers of the defective gene may be identified during genetic counseling, and prenatal diagnosis is also possible. Resources BOOKS

“Nutritional Disorders of the Neuromuscular Transmission and of Motor Neurons.” In Nelson Textbook of Pediatrics, edited by Richard E. Behrman, et al. Philadelphia: W. B. Saunders Company, 2004. Maertens, Paul, and Paul Richard Dyken. “Storage Diseases: Neuronal Ceroid-Lipofuscinoses, Lipidoses, Glycogenoses, and Leukodystrophies.” In Textbook of Clinical Neurology, edited by Christopher G. Goetz. Philadelphia: W. B. Saunders Company, 2003. McGovern, Margaret M., and Robert J. Desnick. “Lysosomal Storage Diseases.” In Textbook of Clinical Neurology, edited by Christopher G. Goetz. Philadelphia: W. B. Saunders Company, 2003. WEBSITES

Genetics Home Reference. National Library of Medicine, National Institutes of Health. (April 27, 2004). . National Institute of Neurological Disorders and Stroke (NINDS). (April 27, 2004). Gaucher Disease Fact Sheet. . ORGANIZATIONS

Center for Jewish Diseases, Department of Human Genetics, Mount Sinai Medical Center. Fifth Avenue at 100th Street, New York, NY 10029. (212) 659-6774 or (212) 241-6947. .

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❙ Gene therapy Definition

Classic gene therapy is the direct use of genetic material in the treatment of disease. This usually involves inserting a functional gene or DNA fragment into key cells to mitigate, or cure, a disease. A broader definition of gene therapy includes all applications of DNA technology to treat disease. For people with certain neurological conditions such as Parkinson’s disease and Canavan disease, initial gene therapy trials have shown promise. Developing gene therapies for treating disorders of the nervous system poses unique challenges, such as how to introduce the therapeutic gene across the blood-brain barrier or how to target the therapeutic gene to one specific area of the brain.

Purpose Genes play a role in every function of the human body. Defects or mutations within a gene can lead to malfunction or disease of cells, tissues, and/or organs. Although standard drug therapy is usually effective in treating the symptoms of a disorder, a patient may be required to take the drugs for an extended time and there may be serious or unpleasant side effects. However, a patient may be cured with few negative consequences if treatment can be targeted directly at the specific cause of the disease (the gene defect), or if that cause can be neutralized or reversed. Therefore, gene therapy provides an attractive alternative to drug therapy as it seeks to provide treatment strategies that will be more complete and less toxic to the patient. Furthermore, gene therapy may provide a way of treating diseases that cannot be managed by standard therapies.

Description There are many diverse approaches to gene therapy since the biological basis of each disease is unique, presenting a different set of parameters and challenges. However, in each case, a basic set of criteria must be met. First,

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Single gene disorders resulting in a loss of gene function in one specific target tissue provide the easiest options for gene therapy, though strategies for many types of mutations have been investigated. A broad spectrum of diseases has been considered for gene therapy, including: • neurological disorders, e.g., Parkinson disease, Huntington disease • muscular dystrophies • immunological disorders, e.g., severe combined immunodeficiency syndrome (SCIDS) • blood abnormalities, e.g., thalassemias, hemophilia • cancer Unfortunately, many of the more commonly occurring disorders, including heart disease, diabetes, and high blood pressure, result from defects in multiple genes making them unlikely candidates for gene therapy using existing technologies. For each disease, it must be determined if ex vivo or in vitro technology is the best approach. In ex vivo technology, patient cell samples are collected and cultured in the laboratory. The new gene is incorporated into the growing cells, and these are subsequently transferred back into the patient. Not all of the cultured cells will include the new gene, and not all will survive the transfer. The hope is that a sufficient number of the modified cells will be functional in the patient such that the therapy will reverse the disease. In vitro therapy involves injecting the new gene directly into the target tissue where the individual cells must pick it up. Of the two, this method is technically easier and cheaper, but it is harder to determine how many of the target cells actually acquire the new gene. Ex vivo therapy is more expensive and time consuming, but allows greater control of the conditions. Both processes require the use of a vector to get the new gene across the cell membrane and into a cell. Viruses have proven to be highly effective as vectors since these are biological entities with a natural function of infecting

host cells. DNA technology allows viruses to be manipulated to replace the normal payload of disease-causing genetic material with therapeutic genes. The virus will retain its ability to infect a host cell but, instead of causing a disease, it will deposit the new gene into the cell. Other mechanisms of gene transfer have also been investigated. Artificial chromosomes have been developed, but these are often too large to move across cell membranes. Liposomes, structures with lipid membranes, that encompass genetic material can be successfully used as vectors if the liposome is absorbed by the cell or if its membrane fuses with the cell membrane releasing the new gene inside the cell. Once the gene enters the cell, one of two things occurs. It may be degraded and lost, which is an unfavorable outcome. Preferably, the gene will stably incorporate into the DNA of the target cell so that it can be processed as a normal part of that genome. If the gene therapy is designed to replace a defective gene, the best-case scenario is for the new gene to integrate into a completely renewable cell such as a stem cell. Theoretically, in this situation, the gene will be permanently incorporated into the patient’s body and no further therapy will be required. Alternatively, if the gene integrates into a genome of a cell with a finite lifespan, the beneficial effects of the gene will only exist while that cell lives, requiring the gene therapy to be repeated at a later time. One of the early successes of gene therapy was for a four-year-old girl with adenine deaminase (ADA) deficiency. This is a form of SCIDS that results in malfunction of the immune system and can lead to death as a result of severe infection. Conventional treatment had failed for this patient, making her a candidate for gene therapy. A normal ADA gene was incorporated into a retroviral vector that transferred the gene into the patient’s lymphocytes in vitro. The modified cells were returned to her circulation by transfusion. After five months, her levels of ADA activity had risen from less than 1% to 50%. With additional therapies over the next two years, her health improved as the enzyme activity stabilized, and she was able to begin a normal life. Twelve years later, she still demonstrates reasonable levels of ADA activity, but the gene therapy was not a cure as she must continue to receive the standard enzyme replacement therapy to maintain her health. Acquired diseases can also be treated with gene therapy as demonstrated by a novel strategy for treating brain cancer. The thymidine kinase (TK) gene from the herpes simplex virus (HSV) has an enzymatic property that converts the drug ganciclovir into a toxic substance that can kill human cells. It was postulated that this could be used as a targeted killing tool. To investigate, cloned HSV TK

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it is essential to fully understand the disease to be treated. The cells or tissues associated with the disease must be well defined and accessible. The gene and the specific mutation or mutations causing the disease must be known, and it must be possible to isolate or synthesize a normal, functional copy of that gene and to incorporate it into a vector. The vector then transfers the new gene to the target cells where, hopefully, the gene will become fully active. The most common roles for the expressed gene include replacing a defective gene, inhibiting or degrading a deleterious DNA, RNA, or protein, or directly or indirectly killing the cell.

Gene therapy

Key Terms DNA Deoxyribonucleic acid; the genetic material in cells that holds the inherited instructions for growth, development, and cellular functioning.

RNA Ribonucleic acid, a nucleic acid that transmits messages in the DNA to other elements in the cell.

Gene A building block of inheritance, which contains the instructions for the production of a particular protein, and is made up of a molecular sequence found on a section of DNA. Each gene is found on a precise location on a chromosome.

Severe combined immunodeficiency syndrome (SCIDS) A group of rare, life-threatening diseases present at birth, that cause a child to have little or no immune system. As a result, the child’s body is unable to fight infections.

Mutation A permanent change in the genetic material that may alter a trait or characteristic of an individual, or manifest as disease. This change can be transmitted to offspring.

Vector A carrier organism (such as a fly or mosquito) that serves to deliver a virus (or other agent of infection) to a host. Also refers to a retrovirus that had been modified and is used to introduce specific genes into the genome of an organism.

Recombinant DNA DNA that has been altered by joining genetic material from two different sources. It usually involves putting a gene from one organism into the genome of a different organism.

genes were injected into brain tumors. In the brain, only the tumor cells are dividing, so these are the only cells that will be infected by the viral vector, and are thus the only cells that will receive the HSV TK gene. When the patient is subsequently treated with ganciclovir, the tumor cells that have incorporated the HSV TK gene will be selectively killed. Clinical trials proved that tumor cells could be selectively eliminated by demonstrating a reduction in the size of the brain tumors in seven of nine patients. A completely different set of therapies is possible if the idea of gene therapy includes the use of DNA for patient treatment in ways other than inserting new genes into cells. One example is the drug Gleevec that was approved in 2001 for use in patients with chronic myelogenous leukemia (CML). Gleevec is a substance that binds to the defective protein produced in CML, blocking that protein’s activity and alleviating the symptoms of the disease. This is a targeted therapy that affects only the cells with the CML mutation, so there are very few side effects. Recombinant DNA technology has also been utilized to generate genetically engineered copies of vaccines (Recombivax HB), antibodies, and normal gene products (insulin).

Aftercare If the new DNA can be stably incorporated into the proper regenerative target cells, the patient may be cured of disease. No additional care should be required, although periodic monitoring of the patient is appropriate.

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Virus A small infectious agent consisting of a core of genetic material (DNA or RNA) surrounded by a shell of protein. A virus needs a living cell to reproduce.

For gene therapies in which the new DNA is inserted into cells with a finite lifespan, the therapeutic effect will be lost when those cells die. In these situations, the patient will require continuing treatments. Monitoring of patients who receive drugs and substances arising from recombinant DNA technology is the same as standard drug therapy.

Precautions Currently classic gene therapy is still experimental. Although many patients have shown significant improvement following their treatment, at least two individuals have died as a result of this type of therapy. Therefore, experts carefully review all protocols before any studies are undertaken. Initial research is done in an animal model system, and any problems detected are carefully evaluated before the same treatments are attempted in humans.

Risks A patient who is receiving gene therapy may face a number of potential problems. The viral vectors used may cause infection and/or inflammation of tissues, and artificial introduction of viruses into the body may initiate other disease processes. Functional gene therapy relies on stable incorporation of a new gene into an individual’s own DNA. As the integration is random, occasionally the new gene may insert within another normally functioning gene, causing its damage or inactivation. This, in turn, could lead to cancer or other disease. It is also critical that the new

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deal of public attention. The TSEs, including GerstmannStraussler-Scheinker disease, involve abnormal clumps of protein that accumulate throughout the brain, destroying brain tissue and leaving spongy holes.

Demographics

Normal results Classic gene therapy seeks to treat or cure a defined disease by incorporating a functional gene or gene product into target cells of an affected individual. Resources BOOKS

George, Linda. Gene Therapy. Woodbridge, CT: Blackbirch Marketing, 2003. Nussbaum, Robert L., Roderick R. McInnes, and Huntington F. Willard. Thompson and Thompson Genetics in Medicine, 6th edition. Philadelphia, PA: W. B. Saunders Company, 2001. Strachan, T., and Andrew P. Read. Human Molecular Genetics, 2nd edition. New York, NY: John Wiley and Sons, 1999. OTHER

National Cancer Institute. Questions and Answers about Gene Therapy. Cited January 4, 2004 (March 23, 2004). .

Constance K. Stein

❙ Gerstmann-StrausslerScheinker disease

Definition Gerstmann-Straussler-Scheinker disease is a progressively disabling and ultimately fatal brain infection caused by a unique protein particle called a prion. Gerstmann-Straussler-Scheinker disease is an inherited disorder, and occurs in familial clusters.

Description Gerstmann-Straussler-Scheinker disease belongs to a group of diseases originally known as slow virus infections. Currently, slow virus infections are classed together as transmissible spongiform encephalopathies (TSE), or prion diseases. Other TSEs include kuru, CreutzfeldtJakob disease, and fatal familial insomnia. The TSE called new variant Creutzfeldt-Jakob disease (also known colloquially as “Mad Cow Disease”) has received a great

About 10% of all transmissible spongiform encephalopathies are inherited. Gerstmann-StrausslerScheinker disease occurs worldwide, but because of its pattern of familial transmission, cases tend to occur in specific geographic clusters. Only a few families have been identified as carrying the mutation that causes GerstmannStraussler-Scheinker disease. Gerstmann-Straussler-Scheinker disease is caused by a genetic mutation caused by an infectious protein particle called a prion, which stands for proteinaceous infectious particle. A prion is similar to a virus, except that it lacks any nucleic acid, which prevents it from reproducing. Prions are abnormal versions of proteins that are found in the membranes of normal cells. These abnormal proteins can be passed directly to individuals through the ingestion of prion-infected tissue or when open sores on the recipient’s skin are exposed to prion-infected tissue. In addition to being transmissible (as are other infectious agents like viruses or bacteria), prions are unique because they can also be acquired through genetic inheritance. This is the case with Gerstmann-Straussler-Scheinker disease. In Gerstmann-Straussler-Scheinker disease, one of several possible specific gene mutations is present, leading to the abnormal deposition of tangled masses of a protein called amyloid throughout the brain. The spinocerebellar tracts (nerves that run from the brain’s cerebellum throughout the spinal cord ) become increasingly atrophied (shrunken) and dysfunctional over time. Symptoms of Gerstmann-Straussler-Scheinker disease tend to begin in later middle age, usually between the ages of 40 and 55. Early symptoms include unsteady gait and difficulty walking, discoordination, clumsiness. As the disease progresses, the individual experiences difficulty speaking; abnormal, involuntary, rapid darting eye movements; paralyzed eye movement; deafness; blindness; and dementia. Death often occurs within five to 10 years of the initial symptoms.

Diagnosis Diagnosis of Gerstmann-Straussler-Scheinker disease is arrived at through characteristic abnormalities found on the electroencephalogram (EEG), a test of brain waves and electricity. MRI studies and biopsies (tissue samples) from the brain may also show changes that are characteristic of

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gene have the proper regulatory controls so that the gene product is produced in the proper amount. Over-expression of certain genes can have deleterious results. Any of these problems could render the gene therapy ineffective, or, at worst, cause the death of the subject.

Gerstmann syndrome

Special Concrns

Key Terms Classic Creutzfeldt-Jakob disease A rare, progressive neurological disease that is believed to be transmitted via an abnormal protein called a prion. Fatal familial insomnia A rare, progressive neurological disease that is believed to be transmitted via an abnormal protein called a prion. Gerstmann-Sträussler-Scheinker syndrome A rare, progressive neurological disease that is believed to be transmitted via an abnormal protein called a prion. New variant Creutzfeldt-Jakob disease A more newly identified type of Creutzfeldt-Jakob disease that has been traced to the ingestion of beef from cows infected with bovine spongiform encephalopathy. Known in the popular press as Mad Cow Disease. Transmissible spongiform encephalopathy A term that refers to a group of diseases, including kuru, Creutzfeldt-Jakob disease, Gerstmann-SträusslerScheinker syndrome, fatal familial insomnia, and new variant Creutzfeldt-Jakob disease. These diseases share a common origin as prion diseases, caused by abnormal proteins that accumulate within the brain and destroy brain tissue, leaving spongy holes.

prion disease. Like certain forms of CJD, GerstmannStraussler-Scheinker disease can be analyzed with DNA testing; specifically, the white blood cells are examined in order to identify one of the mutations associated with the disease.

Treatment team

Gerstmann-Straussler-Scheinker disease is unique among transmissible spongiform encephalopathies, because mutations can be identified through DNA analysis of a sufferer’s white blood cells. This allows other family members to be counseled regarding their personal risk of disease inheritance, projected age of disease onset, and potential illness duration. While some mutations sentence an individual to certain disease, other locations of mutations have only a 50% chance of leading to actual disease. Additionally, in families known to carry a mutation of Gerstmann-Straussler-Scheinker disease, amniocentesis can identify fetuses affected by the mutation, allowing families to make decisions about whether or not to continue a pregnancy. Resources BOOKS

Berger, Joseph R., and Avindra Nath. “Slow virus infections.” In Cecil Textbook of Medicine, edited by Thomas E. Andreoli, et al. Philadelphia: W. B. Saunders Company, 2000. Brown, Paul. “Transmissible Spongiform Encephalopathy.” In Textbook of Clinical Neurology, edited by Christopher G. Goetz. Philadelphia: W. B. Saunders Company, 2003. Murray, T. Jock, and William Pryse-Phillips. “Infectious diseases of the nervous system.” In Noble: Textbook of Primary Care Medicine, edited by John Noble, et al. St. Louis: W. B. Saunders Company, 2001. PERIODICALS

Sy, Man-Sun, Pierluigi Gambetti, and Wong Boon-Seng. “Human Prion Diseases.” Medical Clinics of North America 86 (May 2002): 551–571. WEBSITES

National Institute of Neurological Disorders and Stroke (NINDS). NINDS Gerstmann-Straussler-Scheinker Disease Information Page. March 26, 2003 (June 4, 2004). .

Rosalyn Carson-DeWitt, MD

Diagnosis of slow virus infection is usually made by a neurologist.

Treatment There are no available treatments for GerstmannStraussler-Scheinker disease. It is relentlessly progressive, incurable, and fatal. Supportive care for the patient and his or her family is the only treatment.

Prognosis Gerstmann-Straussler-Scheinker disease is always fatal. 386

❙ Gerstmann syndrome Definition

Gerstmann syndrome is a cluster of neurological symptoms that includes difficulty writing (dysgraphia or agraphia), difficulty with arithmetic (dyscalculia or acalculia), an inability to distinguish left from right, and difficulty identifying fingers (finger agnosia).

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Two types of Gerstmann syndrome have been identified: an acquired form that occurs in adults who have suffered brain injury through stroke or trauma, and a developmental form that has been noted in children. The brain area that seems to be primarily responsible for the deficits seen in Gerstmann syndrome appears to be the parietal lobe, which is located behind the frontal lobe. Current research has not identified a tendency for the developmental form of Gerstmann syndrome to be inherited. Although both adults and children with Gerstmann syndrome may have considerable impairment, they do not necessarily have abnormal intelligence.

Demographics Gerstmann syndrome is usually identified in adult patients who have a history of brain injury or stroke. A very small group of children have also been identified as having the developmental form of the condition. Although the diagnosis tends to be made in school-aged children (usually at the point when writing and calculating become central classroom tasks), the condition may well be congenital. There are no reports clarifying the frequency or incidence of either the acquired or the developmental forms of Gerstmann syndrome.

Causes and symptoms In adults, Gerstmann syndrome may be acquired when bleeding into the brain during a stroke or after a traumatic head injury occurs in an area of the left parietal lobe called the angular gyrus. A few adult cases of Gerstmann syndrome have also been described after viral encephalitis, tumor, or toxic exposure has caused injury to this same area of the brain. A specific cause for developmental Gerstmann syndrome has not been identified, although the fact that both parietal lobes are affected suggests that the problem occurs some time during early brain development. The core symptoms in Gerstmann syndrome include: • dysgraphia or agraphia: an inability or impairment in the ability to express oneself through the written word. • dyscalculia or acalculia: an inability to perform basic calculations. • left-right confusion: difficulty identifying the left or right of one’s body or of other objects. • finger agnosia: an inability to identify one’s own or someone else’s finger on the basis of a verbal command to hold up a particular finger. Adults with Gerstmann syndrome may also display some degree of aphasia, which is an impaired ability to

Key Terms Acalculia The inability to perform basic calculation (addition, subtraction, multiplication, division). Agraphia The inability to write. Angular gyrus A particular ridge (outfolding) in the parietal lobe of the brain. Aphasia Difficulty language.

using

or

understanding

Apraxia Difficulty performing a voluntary movement, although the muscles necessary are all functional. Constructional apraxia Difficulty or inability to copy a drawing. Dyscalculia Difficulty with basic arithmetic and calculations. Dysgraphis Difficulty writing. Finger agnosia Inability to identify a particular finger. Parietal lobes The brain lobes on top of the brain, behind the frontal lobes.

communicate verbally, to understand verbal communication, and to understand written language. Children with developmental Gerstmann syndrome may also exhibit poor handwriting, difficulty spelling, reading problems, and difficulty copying simple drawings (called constructional apraxia).

Diagnosis Diagnosis is through a comprehensive neurological exam and through psychoeducational testing.

Treatment team The treatment team may include a neurologist, behavioral pediatrician, psychologist, psychiatrist, occupational therapist, physical therapist, and educational specialist.

Treatment There is no cure for Gerstmann syndrome. Neither children nor adults with this disorder will recover completely from its effects. Instead, supportive therapy may teach some skills, but will also help identify bypass strategies that can be used. For example, if the arithmetic facts cannot be learned, then the use of calculators and other resources should be encouraged. Word processing programs

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Description

Glossopharyngeal neuralgia

on computers, including those that have voice-recognition capability, can greatly assist someone with Gerstmann syndrome with the tasks of writing. Classroom accommodations for children with Gerstmann syndrome can help assure success.

Giant cell inclusion disease see Cytomegalic inclusion body disease Gilles de la Tourette syndrome see Tourette syndrome

Prognosis Gerstmann syndrome is a permanent disorder. It will last an individual’s lifetime. However, the prognosis can be very good if the patient is helped to understand his or her deficits, supported in using effective bypass strategies, and encouraged to continue developing his or her areas of strength.

Special concerns

Globoid cell leukodystrophy see Krabbe disease

❙ Glossopharyngeal neuralgia Definition

Good diagnosis and support is necessary so that individuals with Gerstmann syndrome can maintain the strongest possible self-esteem. Care must be taken not to suggest that the individual’s failed efforts are due to laziness or lack of caring. Instead, the neurological basis of the disorder should be clearly explained, and reasonable bypass strategies should be immediately identified and implemented. Resources BOOKS

Cummings, Jeffrey L. “Disorders of Cognition.” In Cecil Textbook of Internal Medicine, edited by Lee Goldman, et al. Philadelphia: W. B. Saunders Company, 2000. Mesulam, M. Marsel. “Aphasias and Other Focal Cerebral Disorders.” In Harrison’s Principles of Internal Medicine, edited by Eugene Braunwald, et al. New York: McGrawHill Professional, 2001. Swanberg, Margaret M., et al. “Speech and Language.” In Textbook of Clinical Neurology, edited by Christopher G. Goetz. Philadelphia: W. B. Saunders Company, 2003. PERIODICALS

Roux, F. E. “Writing, Calculating, and Finger Recognition in the Region of the Angular Gyrus: A Cortical Stimulation Study of Gerstmann Syndrome.” Journal of Neurosurgery 99 (November 2003): 716–727. Kronenberger, William G., and David W. Dunn. “Learning Disorders.” Neurologic Clinics 21 (November 2003): 941–952. OTHER

National Institute of Neurological Disorders and Stroke (NINDS). NINDS Gerstmann’s Syndrome Information Page. March 21, 2003 (June 9, 2004). .

Rosalyn Carson-DeWitt, MD 388

Giant cell arteritis see Temporal arteritis

Glossopharyngeal neuralgia is a chronic pain syndrome that causes intense, shooting pains in the back of the tongue and throat, tonsillar areas, and middle ear.

Description Glossopharyngeal neuralgia may be due to inflammation or compression of either the glossopharyngeal nerve or the vagus nerve, another nerve that innervates (stimulates) the same basic areas. The condition usually comes on quite suddenly, and may wax and wane in severity over time. This condition may occur in conjunction with trigeminal neuralgia (a pain syndrome affecting the face).

Demographics Glossopharyngeal neuralgia usually strikes people over the age of 40. It is a relatively rare condition, affecting about 0.7/100,000 individuals per year.

Causes and symptoms The cause of glossopharyngeal neuralgia is not completely understood, although it seems that conditions (tumors, infections, injuries, or blood vessels located close to the glossopharyngeal nerve) that put pressure on the glossopharyngeal nerve may sometimes be responsible for its development. Individuals with diabetes or multiple sclerosis may also develop glossopharyngeal neuralgia. Episodes of pain may be brought on by swallowing, sneezing, chewing, clearing the throat, eating spicy foods, drinking cold liquids, speaking, laughing, or coughing. Glossopharyngeal neuralgia causes sudden, intense pains in the throat, mouth, tongue, jaw, ear, and neck. The pains have been described as excruciating and electric shock-like, and usually last from seconds to several minutes. Because the glossopharyngeal nerve also affects heart rate and blood pressure, some patients experience

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Diagnosis The diagnosis is usually strongly suspected from the patient’s characteristic description of the pain episodes. Often, the doctor can trigger an episode by gently touching the back of the throat with a cotton swab. The test is then repeated after application of a topical anesthetic has been used to numb the throat. If the pain episodes are caused by glossopharyngeal neuralgia, touching the back of the anesthetized throat with a cotton swab will not trigger an episode of pain.

Hermanowicz, Neal. “Cranial Nerves IX (Glossopharyngeal) and X (Vagus).” In Textbook of Clinical Neurology, edited by Christopher G. Goetz. Philadelphia: W. B. Saunders Company, 2003. PERIODICALS

Rozen, Todd D. “Trigeminal neuralgia and glossopharyngeal neuralgia.” Neurologic Clinics 22, no. 1 (February 2004). WEBSITES

NINDS Glossopharyngeal Neuralgia Information Page. National Institute of Neurological Disorders and Stroke (NINDS). November 6, 2002 (June 2, 2004).

Rosalyn Carson-DeWitt, MD

CT or MRI may reveal inflammation of the glossopharyngeal nerve or the presence of an abnormality (such as a tumor) that is exerting pressure on the nerve. Angiography involves introducing dye into the vascular system, in order to take x-ray, CT, or MRI images that may reveal the location of a blood vessel that is exerting pressure on the glossopharyngeal nerve.

Treatment team Neurologists and otorhinolaryngologists treat glossopharyngeal neuralgia.

❙ Glucocorticoids Definition

Glucocorticoids are naturally-produced steroid hormones, or synthetic compounds, that inhibit the process of inflammation.

Purpose Treatment Carbamazepine, phenytoin, gabapentin, baclofen, and tricyclic antidepressants may be used to ameliorate the pain of glossopharyngeal neuralgia. When a blood vessel is identified as compressing the glossopharyngeal nerve, surgery may be performed to move the vessel or to position a Teflon felt pad between the blood vessel and the nerve, in order to attempt to mitigate any pressure that is exerted on the nerve. In severe cases of glossopharyngeal neuralgia that don’t respond to other treatments, surgery that severs the glossopharyngeal nerve may be the only treatment that relieves the sufferer’s pain.

Prognosis The prognosis of glossopharyngeal neuralgia varies, depending on the underlying cause of the disorder. Some individuals are completely relieved of the pain episodes after surgery; others continue to have periodic exacerbations throughout their lives. Resources BOOKS

Cutrer, F. Michael, and Michael A. Moskowitz. “Headaches and Other Head Pain.” In Cecil Textbook of Internal Medicine, edited by Lee Goldman, et al. Philadelphia: W. B. Saunders Company, 2000.

The target of glucocorticoids: inflammation Glucocorticoids are used to stop the inflammation process. The inflammatory process has evolved in the body for a useful purpose; namely as a defensive reaction to the damage or injury to tissue. By a series of reactions, inflammation is designed to isolate whatever is causing the irritation, help eradicate the presumed invader, and help repair the surrounding damaged tissue. The hallmarks of inflammation are redness, heat, swelling, and pain. These reactions arise from the various steps in the inflammation pathway. The inflammatory response begins with the expansion of the capillaries, which allows more blood to flow to the target site. Various proteins from the blood then exit the blood and gather at the target site. Ultimately, white blood cells called leukocytes also accumulate at the site of injury. When these processes occur in response to an invader such as a microorganism, this is beneficial for the body, as it can rid the body of a potential problem. However, sometimes the inflammatory response can persist long after the actual problem is gone, or can be maintained if an infection itself becomes chronic, or can be activated by some malfunction in the body’s defense mechanisms. Chronic inflammation of this type can cause damage to host tissue. Examples of processes that can produce chronic inflammation are tuberculosis, inflammatory bowel diseases such as ulcerative

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abnormal heart rhythms during episodes of pain. The heart rate may become so slow, in fact, that the patient faints.

Glucocorticoids

the manufacturer, dexamethasone is marketed as Decadron, Dexameth, Dexone, and Hexadrol.

Key Terms Osteoporosis A disorder involving loss of calcium and density in the bones, resulting in brittle bones and changes in posture. Steroid A naturally-occurring hormone, and a large class of drugs that chemically resemble cholesterol. Among the more common types of steroids, anabolic steroids are sometimes used illegally in athletics, and glucocorticoid steroids are used to reduce inflammation.

colitis and Crohn’s disease, silicosis, and the continued presence of a foreign body in a wound. Glucocorticoids can be prescribed to dampen or stop entirely this chronic inflammatory chain of events. Depending on the particular glucocorticoid that is used, inflammation can be affected at different points in the inflammatory pathway.

Description Some of the various glucocorticoids can be naturally produced in the body. Chemically, these are steroid hormones. They are different from the infamous anabolic steroids that some athletes use to increase muscle mass and strength. Rather, glucocorticoids are catabolic steroids, meaning they are designed to break down compounds. Natural glucocorticoids are produced in the adrenal glands located immediately above the kidneys (the word adrenal derives from “ad,” meaning top of, and “renal,” meaning kidney). The region of the adrenal glands called the cortex is the site of glucocorticoid manufacture. Glucocorticoids can also be artificially made, and are usually referred to as glucocorticoid drugs. Examples of glucocorticoids are prednisone, prednisilone, methylprednisilone, dexamethasone, and hydrocortisone. Glucocorticoids are usually taken orally as tablets, capsules, syrup, and liquid, with the exception of hydrocortisone (which is applied as a cream). Most can also be used in cream form, and some can be applied as drops to relieve eye irritations. Prednisone is the commonly prescribed glucocorticoid because of its high activity. In the body prednisone is transformed by the liver into prednisolone. Prednisolone is equally as effective and is often prescribed by physicians instead of prednisone. Dexamethasone can be prescribed in higher doses than the other glucocorticoids. A common use for this compound is the reduction of nerve swelling following nerve damage or neurosurgery. Depending on 390

Glucocorticoids and metabolism As well as affecting the inflammatory process, glucocorticoids have an effect on the utilization of compounds in the body (metabolism). Indeed, the designation glucocorticoid arose from observations that the hormones played a role in the utilization of glucose. In an absence of food, which can be broken down to supply glucose, glucocorticoids act to increase and maintain the normal levels of glucose in the blood. They accomplish this by stimulating glucose production by cells, particularly in the liver, and by enhancing the breakdown of fat in fat tissue. As well, glucocorticoids curb the storage of glucose in cells of the body, which leaves the sugar ready for use. Glucocorticoids and inflammation Glucocorticoids are global in their inhibition of the inflammatory response. That is, they act at different stages in the process, and affect all types of inflammatory responses no matter what stimulated the response. The action of glucocorticoids has to do with their structure. Their shape permits them to move across the membrane that surrounds cells in the body, and to be recognized by molecules inside the cell called glucocorticoid receptors. Binding of the particular glucocorticoid to a receptor forms a complex between the two molecules. This complex can enter the nucleus of the cell (the zone where the genetic material is located, and where the two-step process whereby nucleic acid forms the blueprint for the manufacture of the protein building blocks of the cell takes place). Within the nucleus, the complex affects the manufacture of the proteins. The production of some proteins is enhanced while the manufacture of other protein species is diminished. The latter are proteins involved in inflammation and in the release of a normally membrane-bound molecule that acts as a signal for inflammation to begin. The end result is the suppression of inflammation.

Recommended dosage The prescribed dosages of glucocorticoids vary depending on the compound used and the nature of the patient’s condition. Depending on the glucocorticoid, the dose may be taken once a day, over the course of several doses spaced evenly throughout the day, or even every other day.

Precautions As with any prescription drug, the recommended daily dosage and schedule for the drugs should not be changed independent of a physician’s notification. As well, side effects associated with the long-term use of glucocorticoids can occur.

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Prolonged use of glucocorticoids may cause a number of adverse effects. These include the suppression of the immune system (which makes the person more susceptible to infections), osteoporosis, shifts in the body’s fluid balance, skin changes, changes in brain chemistry, and altered behavior. Dexamethasone can cause loss of appetite, weight loss, stomach upset, vomiting, drowsiness, headache, confusion, fever, joint pain, and peeling skin. Not all side effects will be present in everyone taking dexamethasone. More severe side effects of glucocorticoid use include development of diabetes (which can occur transiently even with short-term use of the drugs), glaucoma, cataract formation, peptic ulcer, convulsions, and inhibited growth of children. A physician determines whether the potential risks of the particular glucocorticoid outweigh the advantages of its use, and prescribes the minimum dose necessary to achieve the desired effect.

Interactions Interactions between glucocorticoids and other medications can occur. These include anticoagulants (such as aspirin), digoxin, estrogen, oral contraceptives, phenobarbital, some antibiotics, and even some vitamins. Resources BOOKS

Goulding, N. J. Glucocorticoids (Milestones in Drug Therapy). Birkhauser, 2001. Zuckerman, Eugenia, and Julie R. Inglefinger. Coping with Prednisone and Other Cortisone-Related Medicines: It May Work Miracles, but How Do You Handle the Side Effects? St. Martin’s Press, 1998. OTHER

“Dexamethasone oral.” Medline Plus. National Library of Medicine. (May 6, 2004). . “Glucocorticoids Disease Mechanism II: Inflammation.” Stanford University. (May 6, 2004).

Brian Douglas Hoyle, PhD

❙ Guillain-Barré syndrome Definition

Guillain-Barré syndrome (GBS) is an inflammation of the covering that surrounds nerve cells of the brain and spinal cord. The basis of the inflammation is not conclusively known, but is generally considered to arise from a

malfunctioning immune system that recognizes host tissues as being foreign. The inflammation reaction damages the nerves of the brain and spinal cord, producing weakness in the muscles, loss of sensation (such as the sense of touch in the fingers), or outright paralysis. GBS is termed a syndrome rather than a disease because there is no conclusive evidence to support the possibility that a specific disease-causing agent such as a bacteria or a virus is the direct cause of the malady. Infections may be a trigger to the development of GBS, however.

Description The syndrome is named after George Charles Guillen and Jean-Alexandre Barré, French co-authors of a classic paper on the syndrome that was published in 1916. A third author, André Strohl, was not subsequently associated with the syndrome that was the subject of the paper. GBS is a rare and acute disorder. An acute disorder displays a rapid appearance of symptoms, and a rapid worsening of the symptoms. In the case of GBS, symptoms typically appear over just a single day. Most often, symptoms are first noticed in the feet and legs. The symptoms often progress to involve different parts of the body over the next several days to several weeks. In addition, during that time other more severe symptoms can appear. In more than 90% of cases, the symptoms reach their peak by four weeks. The syndrome is an inflammatory disorder, in which a person’s own immune system attacks the nerves outside the brain and the spinal cord. These nerves are known as peripheral nerves. The nerve inflammation that occurs can damage the nerve cells. The covering (sheath) of a fatty material called myelin that surrounds the cells can be lost. This loss is called demyelination. Additionally, the elongated portion of the nerve cell called the axon can be killed. This phenomenon is called denervation. The axon conveys electrical impulses to more distant areas of muscles, and from one nerve cell to another. Demyelination and denervation bring about muscle weakness, loss of sensation, or paralysis because the affected nerves cannot transmit signals to muscles. This loss of signal transmission inhibits the muscles from being able to respond to nerve signals. As well, the brain receives fewer signals and the person can become unable to feel heat, cold, or pain. GBS is also known as Landry-Guillain-Barré syndrome, acute idiopathic polyneuritis, infectious polyneuritis, and acute inflammatory demyelinating polyneuropathy (AIDP). Another malady called chronic inflammatory demyelinating polyradicalneuropathy is possibly related to GBS. It is far less common than GBS (which itself is rare) and persists longer.

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Side effects

Guillain-Barré syndrome

Demographics GBS can occur at any age. However, the syndrome tends to be more prevalent in men and women aged 15–35 years and 50–75 years (a bimodal pattern of age distribution), respectively. Males are slightly more susceptible than females (the ratio of those affected is approximately 1.5 male per female). There is no known racial group that is any more susceptible to GBS, nor any known geographical localization of the syndrome. In the United States, the syndrome is rare. For example, the annual incidence of GBS in the United States ranges from 0.6 to 2.4 cases per 100,000 people. Nonetheless, GBS is the most common cause of neuromuscular paralysis among Americans.

Causes and symptoms Causes The exact cause of GBS is not known. However, bacterial or viral infections may be a trigger for its development. Almost 70% of those who develop GBS have had an infectious illness in the preceding two to four weeks. Examples of infections include sore throat, cold, flu, and diarrhea. Bacteria that have been associated with the subsequent development of GBS include chlamydia, Mycoplasma pneumoniae, and Campylobacter jejuni. The suspected involvement of Campylobacter is noteworthy, as this bacterium is a common contaminant of poultry. Inadequate cooking can allow the microbe to survive and cause an infection in those who consume the food. Thus, there may be a connection between GBS and food quality. The form of GBS that may be associated with the presence of Campylobacter may be particularly severe. For reasons that are unclear, the peripheral nerves can themselves be directly attacked, rather than just the myelin sheath around the nerves. Usually, infections such as those caused by Campylobacter have abated before the onset of GBS. As well, chronic infection with the viruses responsible for mononucleosis, herpes, and acquired immunodeficiency syndrome can prelude the appearance of GBS. The latter is also known as HIV-1 associated acute inflammatory demyelinating polyneuropathy. Other possible associated factors include vaccination (rabies, swine flu, influenza, Group A streptococci), surgery, pregnancy, and maladies such as Hodgkin’s disease and systematic lupus erythematosus. Whether there is direct (causal) connection between infections and maladies and the subsequent development of GBS, or whether the events are only coincidental, is not known. For example, vaccination of Americans against the swine flu in 1976 increased the rate of GBS by less than 392

one case per 100,000 people. Whether this increase was directly due to the vaccine is impossible to determine. Furthermore, more than 99% of people suffering from GBS who have been surveyed by the United States Centers for Disease Control and Prevention (CDC) have not recently been vaccinated. According to the CDC, the chance of developing GBS as a result of vaccination is remote. It is conceivable that the infections or illnesses disrupt the body’s immune system such that autoimmune destruction of nerve cell components occurs. Although this intriguing possibility is favored among many scientists, it remains unsubstantiated. There is no evidence to indicate that GBS is an infection or that it is a genetically linked (heritable) disorder. Symptoms The initial sensation of weakness or paralysis in the toes spreads upward within days to a few weeks to the arms and the central part of the body. In medical terminology, this represents an ascending pattern of spread. The weakness and paralysis can also be accompanied by a tingling sensation, and a cramping or more constant pain in the feet, hands, thighs, shoulders, lower back, and buttocks. Use of the hands and feet can become impaired. More serious development of paralysis can make breathing difficult, even to the point that mechanical ventilation becomes necessary. Other, less typical symptoms include blurred vision, clumsiness, difficulty in moving facial muscles, involuntary muscle contractions, and a pronounced heartbeat. Symptoms that are indicative of an emergency include difficulty in swallowing, drooling, breathing difficulty, and fainting. Progression from the early symptoms to the more severe symptoms can occur very quickly (i.e., 24–72 hours). Typically, the exacerbated condition persists for several weeks. Recovery then typically occurs gradually, and can take anywhere from days to six months or more. In very mild cases, an individual may just have a general feeling of weakness. As the symptoms abate after a few weeks, the person may dismiss the incident as a viral infection, without ever knowing the true nature of the illness.

Diagnosis GBS is suspected if a patient displays muscle weakness or paralysis that has been increasing in severity, especially if an illness has occurred recently. Loss of reflexes such as the knee jerk reaction can be an early clue to a clinician. Clinical data can be useful in diagnosis. For example, a hormone that is involved in maintaining the proper chemical balance of urine can be affected in GBS. The result is

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Autonomic nervous system The part of the nervous system that is concerned with the control of involuntary bodily functions such as breathing, sweating, blinking, and the heartbeat. Axon The long, hairlike extension of a nerve cell that carries a message to a nearby nerve cell. Demyelination Loss of the myelin (a fatty substance) sheath that surrounds and insulates the axons of nerve cells and is necessary for the proper conduction of neural impulses. Neuropathy A disorder of the nervous system or a nerve.

called the syndrome of inappropriate antidiuretic hormone. Antibodies to nerve cells may be present as a result of the body’s immune reaction against its own constituents. Another clue to the diagnosis of GBS can be the finding of muscle weakness by neurological examination. One such test is known as nerve conduction velocity. In this test, the selected nerve is stimulated, usually with surface electrodes contained in a patch that is applied to the surface of the skin. The nerve can be stimulated using a very mild electrical current put out from one electrode, and the resulting electrical activity is recorded by the other electrodes in the patch. The nerve conduction velocity is calculated knowing the distance between electrodes and measuring the time it takes for the impulses to travel from the generating to the measuring electrodes. A person with GBS whose nerves have usually lost some or most of the myelin sheath will display a slower conduction velocity than that displayed by an unaffected person. Electrical impulses travel along the damaged nerve slower than along an undamaged nerve. Muscle response to electrical stimulation can also be measured by electromyography (EMG). In this test, a needle electrode is inserted through the skin into the muscle. When the muscle is stimulated, for example, by contracting it, the resulting visual or audio pattern carries the information about the muscle’s response. The characteristic pattern of wavelengths produced by a healthy muscle (the action potential) can be compared to a muscle in someone suspected of having GBS. When paralysis of the heart muscle is suspected, an electrocardiogram can be used to record the electrical activity of the heart. GBS muscle paralysis can alter the normal pattern of the heartbeat. Finally, an examination of the cerebrospinal fluid by means of a spinal tap (also known as a lumbar puncture)

Treatment team Neurologists, immunologists, physical therapists, occupational therapists, and nurses figure prominently in GBS treatment. The assistance of support groups such as the Guillen-Barré Syndrome Foundation International can also be a useful adjunct to treatment.

Treatment As recently as the 1980s, treatment for GBS consisted of letting the syndrome run its course. While most people recovered completely with time, some people were not as lucky. Those who develop severe symptoms such as breathing difficulty are routinely hospitalized. One medical procedure that can be useful in the treatment of GBS is called plasmaphoresis. It is also known as plasma exchange. In plasmapheresis, antibodyladen blood plasma (the liquid portion of the blood) is removed from the body. Red blood cells are separated and put back into the body with antibody-free plasma or intravenous fluid. The treatment can lessen the symptoms of GBS and hasten recovery time. As of December 2003, it is not known why plasmapheresis works. It is suspected that the removal of antibodies may lessen the effects of the body’s immune attack on the nerve cells. Another procedure that produces similar results involves the administration of intravenous immune globulin (IVIG). Both treatments have been shown to speed up recovery time by up to 50%. IVIG has been shown to be an effective treatment for immune-system-related neuropathies in general. IVIG may act by reducing the amount of anti-myelin antibodies through the binding of the defective antibodies by healthy antibodies contained in the IVIG solution, and in suppressing the immune response. Other treatments are designed to prevent or lessen complications of GBS. For example, choking during eating, because of throat muscle weakness or paralysis, can be prevented using a feeding tube, and formation of blood clots can be lessened by the use of chemicals that thin the blood. The pain associated with GBS can be treated with anti-inflammatory drugs or, if necessary, stronger-acting narcotic medication. For patients who have breathing difficulties, clinicians may first need to supply oxygen, install a breathing tube (intubation), and/or use a mechanical device that helps in breathing. Physical therapy is helpful. Caregivers can move a patient’s arms and legs to help maintain the flexibility

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Key Terms

may detect a higher-than-normal level of protein in the absence of an increase in the number of white blood cells (WBCs). An increase in WBCs is a hallmark of an infection.

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and strength of the muscles. Later in recovery, sessions in a whirlpool (hydrotherapy) can help restore function to arms and legs. Often, therapists will design a series of exercises to be performed when the patient returns home.

Recovery and rehabilitation More than 95% of people afflicted with GBS survive. In about 20% of people, however, muscle weakness and fatigue may remain. Some people find that wearing highly elastic gradient compression stockings beneficial. The stockings produce the greatest compression at the toes, with a tapering-off upwards to the thigh. The effect is to reduce the volume of veins, which increases the rate of blood flow through the veins. The increased blood flow can reduce the feeling of numbness in the toes.

Clinical trials As of early 2004, three clinical trials were recruiting patients, including: • Assessment of chronic Guillain-Barré syndrome improvement with use of 4-aminopyridine. The study, funded by the United States Food and Drug Administration Office of Orphan Products Development, seeks to assess the potential of 4-aminopyridine in increasing the transmission of impulses in damaged nerves. It is hoped that increased nerve activity could restore some lost muscle activity, as has occurred using the drug with those afflicted with multiple sclerosis. The contact is the Spain Rehabilitation Center, University of Alabama at Birmingham, 35249-7330; Jay Meythaler, M.D. (205) 9342088, (email: [email protected]). • Safety, tolerability, and efficacy of rituximab in patients with anti-glycoconjugate antibody-mediated demyelinating neuropathy: a double-blind placebo-controlled randomized trial. While not directly related to GBS, the study concerns the loss of the myelin sheath of nerves and so is relevant. The study, sponsored by the National Institute of Neurological Disorders and Stroke (NINDS), is designed to evaluate the usefulness of rituximab in preventing the antibody damage to nerves. The contact is the National Institutes of Health Patient Recruitment and Public Liaison Office, Building 61, 10 Cloister Court, Bethesda, MD, 20892-4754; (800) 411-1222; [email protected]. • Diagnostic evaluation of patients with neuromuscular diseases. This NINDS-sponsored study is designed to screen patients for other studies and to help train clinicians in the diagnosis of maladies including GBS. The contact information is the same as the above item.

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Prognosis Most of those afflicted with GBS recover completely, although the recovery can in some cases be slow (months to years). Complete recovery usually occurs when the symptoms fade within three weeks of appearing. The typical scenario is for a patient to experience the most weakness from 10–14 days after the appearance of symptoms, with complete recovery occurring within weeks or a few months. In contrast, a poor prognosis can be associated with a rapid appearance of symptoms, use of assisted ventilation for a month or more, severe nerve damage, and with advancing age. While recovery is complete for most of those afflicted with GBS, in 10–20% of cases the symptoms reappear, in 15–20% the neurologic complications can persist and can cause a long-term disability, and 5–10% of those who are afflicted die. The main cause of death historically was from respiratory failure due to muscle paralysis. With mechanical ventilation, respiratory failure in GBS is less often fatal. Currently the main cause of death is malfunctioning of the autonomic nervous system, which controls involuntary processes such as heart rate, blood pressure, and body temperature. Resources PERIODICALS

Quarles, R. H., and M. D. Weiss. “Autoantibodies Associated with Peripheral Neuropathy.” Muscle Nerve (July 1999): 800–822. OTHER

Guillain-Barré Syndrome (GBS) and Influenzae Vaccine. Centers for Disease Control and Prevention. CDC. December 15, 2003 (April 4, 2004). . Fanion, David, and Daniel M. Joyce. “Guillain-Barré Syndrome.” eMedicine. December 12, 2003 (April 4, 2004). . Mayo Foundation for Medical Education and Research. “Guillain-Barré Syndrome.” MayoClinic.com. December 13, 2003 (April 4, 2004). . National Institutes of Health. “Guillain-Barré Syndrome.” MEDLINEplus Medical Encyclopedia. December 13, 2003 (April 4, 2004). . NINDS Guillain-Barré Syndrome Information Page. National Institute of Neurological Disorders and Stroke. December 10, 2003 (April 4, 2004). . ORGANIZATIONS

Centers for Disease Control and Prevention. 1600 Clifton Road, Atlanta, GA 30333. (404) 639-3311 or (800) 3113435. .

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National Institute for Neurological Disorders and Stroke. P.O. Box 5801, Bethesda, MD 20824. (301) 4965761 or (800) 352-9424. .

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Guillain-Barré Syndrome Foundation International. P.O. Box 262, Wynnewood, PA 19096. (610) 667-0131; Fax: (610) 667-7036. [email protected]. . National Institutes of Health. 9000 Rockville Pike, Bethesda, MD 20892. (301) 496-4000. [email protected]. .

H Hallervorden-Spatz disease see Pantothenate kinase-associated neurodegeneration (PKAN)

❙ Hallucination Definitions

A hallucination is a sensory perception without a source in the external world. The English word “hallucination” comes from the Latin verb hallucinari, which means “to wander in the mind.” Hallucinations can affect any of the senses, although certain diseases or disorders are associated with specific types of hallucinations. It is important to distinguish between hallucinations and illusions or delusions, as the terms are often confused in conversation and popular journalism. A hallucination is a distorted sensory experience that appears to be a perception of something real even though it is not caused by an external stimulus. For example, some elderly people who have been recently bereaved may have hallucinations in which they “see” the dead loved one. An illusion, by contrast, is a mistaken or false interpretation of a real sensory experience, as when a traveler in the desert sees what looks like a pool of water, but in fact is a mirage caused by the refraction of light as it passes through layers of air of different densities. The bluish-colored light is a real sensory stimulus, but mistaking it for water is an illusion. A delusion is a false belief that a person maintains in spite of evidence to the contrary and in spite of proof that other members of their culture do not share the belief. For example, some people insist that they have seen flying saucers or unidentified flying objects (UFOs) even though the objects they have filmed or photographed can be shown to be ordinary aircraft, weather balloons, satellites, etc.

Description It would be difficult to describe a “typical” hallucination, as these experiences vary considerably in length of time, quality, and sense or senses affected. Some hallucinations last only a few seconds; however, some people diagnosed with Charles Bonnet syndrome (CBS) have reported visual hallucinations lasting over several days, while people who have taken certain drugs have experienced hallucinations involving colors, sounds, and smells lasting for hours. Albert Hoffman, the Swiss chemist who first synthesized lysergic acid diethylamide (LSD), experienced nine hours of hallucinations after taking a small amount of the drug in 1943. In 1896, the American neurologist S. Weir Mitchell published an account of the six hours of hallucinations that followed his experimental swallowing of peyote buttons. There is not always a close connection between the cause of a person’s hallucinations and the emotional response to them. One study of patients diagnosed with CBS found that 30% of the patients were upset by their hallucinations, while 13% found them amusing or pleasant. The environment in which LSD and other hallucinogens are taken may affect an individual’s psychological constitution and personal reactions. The writer Peter Matthiessen, for example, noted that his 1960s experiences with LSD “were magic shows, mysterious, enthralling,” while his wife “... freaked out; that is the drug term, and there is no better.... her armor had cracked, and all the night winds of the world went howling through.” In contrast to those who take hallucinogens, however, a majority of patients with narcolepsy, alcoholic hallucinosis, or post-traumatic disorders finds their hallucinations frightening.

Demographics The demographics of hallucinations vary depending on their cause; however, many researchers think that they are underreported for several reasons: • Fear of being thought “crazy” or mentally ill

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• Gaps in research. For example, some types of hallucinations are associated with disorders that primarily affect the elderly, who are often underrepresented in health surveys • Fear of being reported to law enforcement for illegal drug use In 2000, one of the few studies of hallucinations in a general Western population reported the following statistics: • Of a total sample of 13,000 adults, 38.7% reported hallucinations: 6.4% had hallucinations once a month, 2.7% once a week, and 2.4% more than once a week. • Of the subjects, 27% reported having hallucinations in the daytime. In this group, visual (3.2%) and auditory (0.6%) hallucinations were closely associated with diagnoses of psychotic or anxiety disorders. • Of the subjects, 3.1% reported haptic (tactile) hallucinations; most of these subjects were current drug users. There is currently no evidence that hallucinations occur more frequently in some racial or ethnic groups than in others. In addition, gender does not appear to make a difference. The demographics of hallucinations associated with some specific age groups, conditions, or disorders are as follows: • Children. Hallucinations are rare in children below the age of eight. About 40% of children diagnosed with schizophrenia, however, have visual or auditory hallucinations. • Eye disorders. About 14% of patients treated in eye clinics for glaucoma or age-related macular degeneration report visual hallucinations. • Alzheimer’s disease (AD). About 40–50% of patients diagnosed with AD develop hallucinations in the later stages of the disease. • Drug use. Hallucinogens are the third most frequently abused class of drugs (after alcohol and marijuana) among high school and college students. Various surveys report that about 7% of people in the United States over the age of 12 have taken LSD at least once; that 5% of high school seniors admit to using MDMA (Ecstasy); and that 20–24% of college students use MDMA. The highest rate of hallucinogen abuse is found in Caucasian males between the ages of 18 and 25. • Normal sleep/wake cycles. Sleep researchers in Great Britain and the United States have reported that 30–37% of adults experience hypnagogic hallucinations, which occur during the passage from wakefulness into sleep, while about 10–12% report hypnopompic hallucinations, which occur as a person awakens. Hallucinations related 398

to ordinary sleeping and waking are not considered an indication of a mental or physical disorder. • Migraine headaches. About 10% of patients diagnosed with migraine headaches experience visual hallucinations prior to the onset of an acute attack. • Adult-onset schizophrenia. According to the National Institute of Mental Health (NIMH), about 75% of adults diagnosed with schizophrenia experience hallucinations, most commonly auditory or visual. The auditory hallucinations may be command hallucinations, in which the person hears voices ordering him or her to do something. For example, the man who killed a Swedish politician in September 2003 told the police that voices in his head told him “to attack.” • Temporal lobe epilepsy (TLE). About 80% of patients diagnosed with TLE report gustatory and olfactory hallucinations as well as auditory and visual hallucinations. • Narcolepsy. Frequent hypnagogic hallucinations are considered one of four classic symptoms of narcolepsy, and are experienced by 60% of patients diagnosed with the disorder. • Post-traumatic stress disorder (PTSD). Studies of combat veterans diagnosed with PTSD have found that 50–65% have experienced auditory hallucinations. Visual, olfactory, and haptic hallucinations have been reported by survivors of rape and childhood sexual abuse.

Causes The neurologic causes of hallucinations are not currently completely understood, although researchers have identified some factors in the context of specific disorders, and have proposed various hypotheses to explain hallucinations in others. There does not appear to be a single causal factor that accounts for hallucinations in all people who experience them. Sleep deprivation Research subjects who have undergone sleep deprivation experiments typically begin to hallucinate after 72–96 hours without sleep. It is thought that these hallucinations result from the malfunctioning of nerve cells within the prefrontal cortex of the brain. This area of the brain is associated with judgment, impulse control, attention, and visual association, and is refreshed during the early stages of sleep. When a person is sleep-deprived, the nerve cells in the prefrontal cortex must work harder than usual without an opportunity to recover. The hallucinations that develop on the third day of wakefulness are thought to be hypnagogic hallucinations that occur during “microsleeps,” or short periods of light sleep lasting about one to ten seconds.

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Amygdala An almond-shaped brain structure in the limbic system that is activated in stressful situations to trigger the emotion of fear. Hallucinations related to post-traumatic stress are thought to be caused by the activation of memory traces in the amygdala that have not been integrated and modified by other parts of the brain. Auditory Pertaining to the sense of hearing. Charles Bonnet syndrome (CBS) A disorder characterized by visual hallucinations following a sudden age-related deterioration in a person’s vision, most commonly glaucoma or macular degeneration. CBS is named for a Swiss doctor who first described it in his visually impaired grandfather in 1780. Command hallucination A type of auditory hallucination in which the person hears voices ordering him or her to perform a specific act. Corollary discharge A mechanism in the brain that allows one to distinguish between self-generated and external stimuli or perceptions. Delusion A false belief that a person maintains in spite of obvious proof or evidence to the contrary. Flashback A vivid sensory or emotional experience that happens independently of the initial event or experience. Flashbacks resulting from the use of LSD are sometimes referred to as hallucinogen persisting perception disorder, or HPPD. Gustatory Pertaining to the sense of taste. Hallucinogen A drug or other substance that induces hallucinations.

Post-traumatic memory formation Hallucinations in trauma survivors are caused by abnormal patterns of memory formation during the traumatic experience. In normal situations, memories are formed from sensory data, organized in a part of the brain known as the hippocampus, and integrated with previous memories in the frontal cortex. People then “make sense” of their memories through the use of language, which helps them to describe their experiences to others and to themselves. In traumatic situations, however, bits and pieces of memory are stored in the amygdala, an almond-shaped structure in the brain that ordinarily attaches emotional significance to memories, without being integrated by the

Haptic Pertaining to the sense of touch; sometimes called tactile hallucinations. Hippocampus A part of the brain that is involved in memory formation and learning. The hippocampus is shaped like a curved ridge and belongs to an organ system called the limbic system. Hypnagogic Pertaining to drowsiness; refers to hallucinations that occur as a person falls asleep. Hypnopompic Persisting after sleep; refers to hallucinations that occur as a person awakens. Illusion A false interpretation of a real sensory image or impression. Irritative hallucinations Hallucinations caused by abnormal electrical activity in the brain. Lysergic acid diethylamide (LSD) The first synthetic hallucinogen, discovered in 1938. Neuroleptic Another name for an antipsychotic medication. Neurotransmitters Chemicals that carry nerve impulses from one nerve cell to another. Olfactory Pertaining to the sense of smell. Psychosis A severe mental disorder characterized by loss of contact with reality. Hallucinations are associated with such psychotic disorders as schizophrenia and brief psychotic disorder. Release hallucinations Hallucinations that develop after partial loss of sight or hearing, and represent images or sounds formed from memory traces rather than present sensory input. They are called “release” hallucinations because they would ordinarily be blocked by incoming sensory data.

hippocampus and interpreted in the frontal cortex. In addition, the region of the brain that governs speech (Broca’s area) often shuts down under extreme stress. The result is that memories of the traumatic event remain in the amygdala as a chaotic wordless jumble of physical sensations or sensory images that can re-emerge as hallucinations during stressful situations at later points in the patient’s life. Irritative hallucinations In 1973, a British researcher named Cogan categorized hallucinations into two major groups that he called “irritative” and “release” hallucinations. Irritative hallucinations result from abnormal electrical discharges in the

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Hallucination

brain, and are associated with such disorders as migraine headaches and epilepsy. Brain tumors and traumatic damage to the brain are other possible causes of abnormal electrical activity manifesting as visual hallucinations. Hallucinations have also been reported with a number of infectious diseases that affect the brain, including bacterial meningitis, rabies, herpes virus infections, Lyme disease, HIV infection, toxoplasmosis, Jakob-Creuzfeldt disease, and late-stage syphilis. Release hallucinations Release hallucinations are most common in people with impaired eyesight or hearing. They are produced by the spontaneous activity of nerve cells in the visual or auditory cortex of the brain in the absence of actual sensory data from the eyes or ears. These experiences differ from the hallucinations of schizophrenia in that those patients experiencing release hallucinations are often able to recognize them as unreal. Release hallucinations are also more elaborate and usually longer in duration than irritative hallucinations. The visual hallucinations of patients with CBS are an example of release hallucinations. Neurotransmitter imbalances Neurotransmitters are chemicals produced by the body that carry electrical impulses across the gaps (synapses) between adjoining nerve cells. Some neurotransmitters inhibit the transmission of nerve impulses, while others excite or intensify them. Hallucinations in some conditions or disorders result from imbalances among these various chemicals. NARCOLEPSY Narcolepsy is a disorder characterized by uncontrollable brief episodes of sleep, frequent hypnagogic or hypnopompic hallucinations, and sleep paralysis. Between 1999 and 2000, researchers discovered that people with narcolepsy have a much lower than normal number of hypocretin neurons, which are nerve cells in the hypothalamus that secrete a neurotransmitter known as hypocretin. Low levels of this chemical are thought to be responsible for the daytime sleepiness and hallucinations of narcolepsy. PRESCRIPTION MEDICATIONS Hallucinations have been reported as side effects of such drugs as ketamine (Ketalar), which is sometimes used as an anesthetic but has also been used illegally to commit date rape; paroxetine (Paxil), an SSRI antidepressant; mirtazapine (Remeron), a serotonin-specific antidepressant; and zolpidem (Ambien), a sleep medication. Ketamine prevents brain cells from taking up glutamate, a neurotransmitter that governs perception of pain and of one’s relationship to the environment. Paroxetine alters the balance between the neurotransmitters serotonin and acetylcholine.

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Hallucinations in patients with Alzheimer’s disease are thought to be a side effect of treatment with neuroleptics (antipsychotic medications), although they may also result from inadequate blood flow in certain regions of the brain. The antiretroviral drugs used to treat HIV infection may also produce hallucinations in some patients. HALLUCINOGENS AND DRUGS OF ABUSE Like the hallucinations caused by prescription drugs, hallucinations caused by drugs of abuse result from disruption of the normal balance of neurotransmitters in the brain. Hallucinations in cocaine and amphetamine users, for example, are associated with the overproduction of dopamine, a neurotransmitter associated with arousal and motor excitability. LSD appears to produce hallucinations by blocking the action of the neurotransmitters serotonin (particularly serotonin-2) and norepinephrine. Phencyclidine (PCP) acts like ketamine in producing hallucinations by blocking the reception of glutamate.

People who have used LSD sometimes experience flashbacks, which are spontaneous recurrences of the hallucinations and other distorted perceptions caused by the drug. Some doctors refer to this condition as hallucinogen persisting perception disorder, or HPPD. There are two types of alcohol withdrawal syndromes characterized by hallucinations. Alcoholic hallucinosis typically occurs after abrupt withdrawal from alcohol after a long period of excessive drinking. The patient hears threatening or accusing voices rather than “seeing things,” and his or her consciousness is otherwise normal. Delirium tremens (DTs), on the other hand, is a withdrawal syndrome that begins several days after drinking stops. A patient with the DTs is disoriented, confused, depressed, feverish, and sweating heavily as well as hallucinating, and the hallucinations are usually visual. MOOD DISORDERS Visual hallucinations occasionally occur in patients diagnosed with depression, particularly the elderly. These hallucinations are thought to result from low levels of the neurotransmitter serotonin. The hallucinations that occur in patients with Parkinson’s disease appear to result from a combination of medication side effects, depressed mood, and impaired eyesight.

Schizophrenia The auditory hallucinations associated with schizophrenia may be the end result of a combination of factors. These hallucinations have sometimes been attributed to unusually high levels of the neurotransmitter dopamine in the patient’s brain. Other researchers have noted abnormal patterns of brain activity in patients with schizophrenia. In particular, these patients suffer from dysfunction of a mechanism known as corollary discharge, which allows people to distinguish between stimuli outside the self and

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Diagnosis The differential diagnosis of hallucinations can be complicated, but in most cases taking the patient’s medical history will help the doctor narrow the list of possible diagnoses. If the patient has been taken to a hospital emergency room, the doctor may ask those who accompanied the patient for information. The doctor may also need to perform a medical evaluation before a psychiatric assessment of the hallucinations can be made. The medical evaluation may include laboratory tests and imaging studies as well as a physical examination, depending on the patient’s other symptoms. If it is suspected that the patient is suffering from delirium, dementia, or a psychotic disorder, the doctor may assess the patient’s mental status by using a standard instrument known as the mini-mental status examination (MMSE) or the Folstein (after the clinician who devised it). The MMSE yields a total score based on the patient’s appearance, mood, cognitive skills, thought content, judgment, and speech patterns. A score of 20 or lower usually indicates delirium, dementia, schizophrenia, or severe depression. Hallucinations in elderly patients may require specialized evaluation because of the possibility of overlapping causes. The American Association for Geriatric Psychiatry lists hallucinations as an indication for consulting a geriatric psychiatrist. In addition, elderly patients should be routinely screened for visual or hearing impairments.

Treatment Hallucinations are treated with regard to the underlying disorder. Depending on the disorder, treatment may involve antipsychotic, anticonvulsant, or antidepressant medications; psychotherapy; brain or ear surgery; or therapy for drug dependence. Hallucinations related to normal sleeping and waking are not a cause for concern.

Prognosis The prognosis of hallucinations depends on the underlying cause or disorder. Resources BOOKS

Altman, Lawrence K., MD. Who Goes First? The Story of Self-Experimentation in Medicine. Berkeley, CA: University of California Press, 1998. American Psychiatric Association. Diagnostic and Statistical Manual of Mental Disorders, 4th edition, text revision. Washington, DC: American Psychiatric Association, 2000. Beers, Mark H., MD. “Behavior Disorders in Dementia.” The Merck Manual of Geriatrics, edited by Mark H. Beers, MD, and Robert Berkow, MD. Whitehouse Station, NJ: Merck Research Laboratories, 2002. “Drug Use and Dependence.” The Merck Manual of Diagnosis and Therapy, edited by Mark H. Beers, MD, and Robert Berkow, MD. Whitehouse Station, NJ: Merck Research Laboratories, 2002. Matthiessen, Peter. The Snow Leopard. New York: Penguin Books USA, 1987. “Psychiatric Emergencies.” The Merck Manual of Diagnosis and Therapy, edited by Mark H. Beers, MD, and Robert Berkow, MD. Whitehouse Station, NJ: Merck Research Laboratories, 2002. “Schizophrenia and Related Disorders.” Section 15, Chapter 193 in The Merck Manual of Diagnosis and Therapy, edited by Mark H. Beers, MD, and Robert Berkow, MD. Whitehouse Station, NJ: Merck Research Laboratories, 2002. PERIODICALS

Braun, Claude M. J., Mathieu Dumont, Julie Duval, et al. “Brain Modules of Hallucination: An Analysis of Multiple Patients with Brain Lesions.” Journal of Psychiatry and Neuroscience 28 (November 2003): 432–439. Cameron, Scott, MD, and Michael Richards, MD. “Hallucinogens.” eMedicine. Cited January 9, 2004 (March 23, 2004). . Chuang, Linda, MD, and Nancy Forman, MD. “Mental Disorders Secondary to General Medical Conditions.” eMedicine. Cited January 30, 2003 (March 23, 2004). . Cowell, Alan. “Swedish Foreign Minister’s Killer Blames ‘Voices’ in His Head.” New York Times. Cited January 15, 2004. Ford, J. M., and D. H. Mathalon. “Electrophysiological Evidence of Corollary Discharge Dysfunction in Schizophrenia During Talking and Thinking.” Journal of Psychiatric Research 38 (January-February 2004): 37–46. Gaser, C., I. Nenadic, H. P. Volz, et al. “Neuroanatomy of ‘Hearing Voices’: A Frontotemporal Brain Structural Abnormality Associated with Auditory Hallucinations in Schizophrenia.” Cerebral Cortex 14 (January 2004): 91–96.

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internal intentions and thoughts. Electroencephalograms (EEGs) of patients with schizophrenia that were taken while the patients were talking showed that corollary discharges from the frontal cortex of the brain (where thoughts are produced) failed to inform the auditory cortex (where sounds are interpreted) that the talking was self-generated. This failure would lead the patients to interpret internal speech as coming from external sources, thus producing auditory hallucinations. In addition, the brains of patients with schizophrenia appear to suffer tissue loss in certain regions. In early 2004, some German researchers reported a direct correlation between the severity of auditory hallucinations in patients with schizophrenia and the amount of brain tissue that had been lost from the primary auditory cortex.

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Gleason, Ondria C., MD. “Delirium.” American Family Physician 67 (March 1, 2003): 1027–1034. Ohayon, M. M. “Prevalence of Hallucinations and Their Pathological Associations in the General Population.” Psychiatry Research 97 (December 27, 2000): 153–164. Pelak, V. S., and G. T. Liu. “Visual Hallucinations.” Current Treatment Options in Neurology 6 (January 2004): 75–83. Rovner, Barry R., MD. “The Charles Bonnet Syndrome: Visual Hallucinations Caused by Vision Impairment.” Geriatrics 57 (June 2002): 45–46. Schneider, L. S., and K. S. Dagerman. “Psychosis of Alzheimer’s Disease: Clinical Characteristics and History.” Journal of Psychiatric Research 38 (JanuaryFebruary 2004): 105–111. Tsai, M. J., Y. B. Huang, and P. C. Wu. “A Novel Clinical Pattern of Visual Hallucination After Zolpidem Use.” Journal of Toxicology: Clinical Toxicology 41 (June 2003): 869–872. OTHER

National Institute of Mental Health (NIMH). Schizophrenia. NIH Publication No. 02-3517. Bethesda, MD: NIMH, 2002. (March 23, 2004). . National Institute on Drug Abuse (NIDA). Research Report: Hallucinogens and Dissociative Drugs. NIH Publication No. 01-4209. Bethesda, MD: NIDA, 2001. ORGANIZATIONS

American Academy of Neurology (AAN). 1080 Montreal Avenue, Saint Paul, MN 55116. (651) 695-2717 or (800) 879-1960; Fax: (651) 695-2791. memberservices@ aan.com. . American Association for Geriatric Psychiatry. 7910 Woodmont Avenue, Suite 1050, Bethesda, MD 208143004. (301) 654-7850; Fax: (301) 654-4137. main@ aagponline.org. . American Psychiatric Association (APA). 1000 Wilson Boulevard, Suite 1825, Arlington, VA 22209-3901. (703) 907-7300. [email protected]. . National Institute of Mental Health (NIMH) Office of Communications. 6001 Executive Boulevard, Room 8184, MSC 9663, Bethesda, MD 20892-9663. (301) 4434513 or (866) 615-NIMH; Fax: (301) 443-5158. [email protected]. . National Schizophrenia Foundation. 403 Seymour Avenue, Suite 202, Lansing, MI 48933. (517) 485-7168 or (800) 482-9534; Fax: (517) 485-7180. inquiries@ nsfoundation.org. . National Sleep Foundation (NSF). 1522 K Street NW, Suite 500, Washington, DC 20005. (202) 347-3471; Fax: (202) 347-3472. [email protected]. .

Rebecca Frey, PhD

Head injury see Traumatic brain injury 402

❙ Headache Definition

Headache is a pain in the head and neck region that may be either a disorder in its own right or a symptom of an underlying medical condition or disease. The medical term for headache is cephalalgia. Headaches are one of the most common and universal human ailments, described in the Bible as well as in medical writings from ancient Egypt, Babylonia, Greece, Rome, India, and China. Severe chronic headaches were once treated by the oldest known surgical procedure, known as trepanning or trephining, in which the surgeon drilled a hole as large as 1–2 in diameter in the patient’s skull without benefit of anesthesia. Evidence of trepanning has been found in skulls from Cro-Magnon people that are about 40,000 years old.

Description Contemporary doctors divide headaches into two large categories, primary and secondary, according to guidelines established by the International Headache Society (IHS) in 1988 and revised for republication in 2004. Primary headaches are those that are not caused by an underlying medical condition. There are three types of primary headaches: migraine, cluster, and tension headaches. More than 90% of all headaches are primary headaches. Secondary headaches are caused by disease or medical condition; they account for fewer than 10% of all headaches. Primary headaches MIGRAINE HEADACHES Migraine headaches are characterized by throbbing or pulsating pain of moderate or severe intensity lasting from four hours to as long as three days. The pain is typically felt on one side of the head; in fact, the English word “migraine” is a combination of two Greek words that mean “half” and “head.” Migraine headaches become worse with physical activity and are often accompanied by nausea and vomiting. In addition, patients with migraine headaches are hypersensitive to lights, sounds, and odors. The two most common types of migraines are known as classic and common migraine, respectively. Classic migraine, which accounts for 10–20% of the cases of migraine, is distinguished by a brief period of warning symptoms 10–60 minutes before an acute attack. This prodrome, which is known as an aura, may include such symptoms as seeing flashing lights or zigzag patterns, temporary loss of vision, difficulty speaking, weakness in an arm or leg, and tingling sensations in the face or hands. Common migraine is not preceded by an aura, although some patients experience mood changes, unusual tiredness, or fluid retention shortly before an attack. An attack

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of common migraine may include diarrhea and frequent urination, as well as nausea and vomiting.

Muscles

Less common types of migraines include hemiplegic migraine, characterized by temporary paralysis on one side of the body; ophthalmoplegic migraine, in which the pain is felt in the area around the eye; basilar artery migraine, which involves a major artery at the base of the brain and primarily affects young women; and headachefree migraine, which is characterized by the gastrointestinal and visual symptoms of classic migraine, but does not involve head pain. CLUSTER HEADACHES Cluster headaches are recurrent brief attacks of sudden and severe pain on one side of the head, usually most intense in the area around the eye. Other names for these headaches include histamine cephalalgia, Horton neuralgia, or erythromelalgia. Cluster headaches may last between five minutes and three hours; they may occur once every other day or as often as eight times per day. The IHS classifies cluster headaches as either episodic or chronic. Episodic cluster headaches occur over periods lasting from seven days to one year, with the clusters separated by headache-free intervals of at least two weeks. The average length of a cluster ranges between two weeks and three months. Chronic cluster headaches occur over a period longer than a year without a headache-free interval, or with pain-free intervals that are shorter than two weeks.

The pain of a cluster headache is excruciating; some patients describe it as severe enough to make them consider suicide. Patients with cluster headaches are restless; they may pace the floor, weep, rock back and forth, or bang their heads against a wall in desperation to stop the pain. In addition to severe pain, patients with cluster headaches often have a runny or congested nose, watery or inflamed eyes, drooping eyelids, swelling in the area of the eyebrows, and heavy facial perspiration. Because of the nasal symptoms and the relative rarity of cluster headaches, these episodes have sometimes been misdiagnosed as sinusitis. TENSION HEADACHES Tension headaches are the

most common headaches in the general population; other names for them include muscle contraction headache, ordinary headache, psychomyogenic headache, and stress headache. The IHS classifies tension headaches as either episodic or chronic; episodic tension headaches occur 15 or fewer times per month, whereas chronic tension headaches occur on 15 or more days per month over a period of six months or longer. Tension headaches rarely last more than a few hours; 82% resolve in less than a day. The patient will usually describe the pain of a tension headache as mild to moderate in severity. The doctor will not find anything abnormal in the course of a general physical or neurological examination, although sore or tense areas (trigger points) in the

Areas of pain

Tension Headache

Tension headaches are caused by severe muscle contractions triggered by stress or exertion. Tension headaches usually occur in the front of the head, although they may also appear at the top or the back of the skull. (Illustration by Electronic Illustrators Group.)

muscles of the patient’s forehead, neck, or upper shoulder area may be detected. REBOUND HEADACHES Rebound headaches, which are also known as analgesic-abuse headaches, are a subtype of primary headache caused by overuse of headache drugs. They may be associated with medications taken for tension and migraine headaches. Secondary headaches Secondary headaches, which are caused by diseases or disorders, are categorized as either traction or inflammatory headaches. Traction headaches result from the pulling, stretching, or displacing of structures that are sensitive to pain, as when a brain tumor presses on the outer layer of nerve tissue that covers the brain. Inflammatory headaches are caused by infectious diseases of the ears, teeth, sinuses, or other parts of the head. Major causes of secondary headaches include the following: • Brain tumors. Headaches associated with brain tumors usually begin as episodic nighttime headaches that are accompanied by projectile vomiting. The headaches may become continuous over time, and usually get worse if the patient coughs, sneezes, bears down while using the

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toilet, or does something else that increases the pressure inside the head. • Meningitis. Meningitis is an inflammation of the meninges, the three layers of membranes that cover the brain and spinal cord. Meningitis is usually caused by bacteria or viruses, and may produce chronic headaches. • Head trauma. Patients may complain of headaches as well as memory problems, general irritability, and fatigue for months or even years after a head injury. These symptoms are sometimes grouped together as post-concussion syndrome. In some cases, a blow on the head may cause some blood vessels to rupture and produce a hematoma, or mass of blood that displaces brain tissue, and can cause seizures or weakness as well as headaches. • Temporal arteritis. First described in 1890, temporal arteritis is an inflammation of the temporal artery that most commonly affects people over 50. In addition to headache, patients with temporal arteritis may have fever, loss of appetite, and blurring or loss of vision. Temporal arteritis is treated with steroid medications. • Stroke. Headaches may be associated with several conditions that may lead to stroke, including high blood pressure and heart disease. Headaches may also result from completed stroke or from the mini-strokes known as transient ischemic attacks, or TIAs. • Lumbar puncture. About 25% of patients who undergo a lumbar puncture (spinal tap) develop a headache from the lowered cerebrospinal fluid pressure around the brain and spinal cord. Lumbar puncture headaches usually go away on their own after a few hours. • Sinus infections. Acute sinusitis is characterized by fluid buildup inside sinus cavities inflamed by a bacterial or viral infection. Chronic sinusitis usually results from an allergic reaction to smoke, dust, animal fur, or similar irritants. • Referred pain. This type of pain is felt in a part of the body at a distance from the injured or diseased area. Headache pain may be referred from diseased teeth; disks in the cervical spine that have been damaged by spondylosis (degeneration of the spinal vertebrae caused by osteoarthritis); or the temporomandibular joint, the small joint in front of the ear where the lower jaw is attached to the skull. • Idiopathic intracranial hypertension. Also known as pseudotumor cerebri, this disorder is caused by increased pressure inside the skull in the absence of any abnormality of the central nervous system or blockage in the flow of the cerebrospinal fluid. In addition to headache, patients with this disorder experience diplopia (seeing double) and other visual symptoms. 404

Demographics Headaches in general are very common in the adult population in North America. The American Council for Headache Education (ACHE) estimates that 95% of women and 90% of men in the United States and Canada have had at least one headache in the past 12 months. Most of these are tension headaches. Tension headaches may begin in childhood in some patients, but most commonly start in adolescence or the early 20s. The gender ratio for episodic tension headaches is about 1.4 F:1 M; for chronic tension headaches, 1.9 F:1 M. Migraine and cluster headaches have distinctive demographic patterns. Migraine headaches are less common than tension headaches, affecting about 11% of the population in the United States and 15% in Canada. Several studies done in the United Kingdom and the United States, however, indicate that doctors tend to underdiagnose migraine headache; thus the true number of patients with migraine may be considerably higher than the usual statistics indicate. Migraines are a major economic burden; it is estimated that the annual cost of time lost from work due to migraines in the United States alone is $17.2 billion. Most people who experience migraines have their first episode in childhood or adolescence, although some experience their first migraine after age 20. Migraines occur most frequently in adults between the ages of 25 and 55; the gender ratio is about 3 F:1 M. Although migraine headaches occur in people of all races and ethnic groups, they are thought to affect Caucasians more often than African or Asian Americans. Currently, migraine is the only type of primary headache known to run in families. A child with one parent affected by migraines has a 50% chance of developing migraines as an adult; if both parents are affected, the risk rises to 70%. Although geneticists think that a number of different genes are involved in transmitting a susceptibility to migraine, they have recently identified two specific loci on human chromosomes 1 and 14, respectively, that are linked to migraine headaches. The locus on chromosome 1q23 has been linked to familial hemiplegic migraine type 2, while the locus on chromosome 14q21 is associated with common migraine. Cluster headaches are the least common type of primary headaches, affecting about 0.4% of adult males in the United States and 0.08% of adult females. The gender ratio is 5–7.5 M:1 F. Cluster headaches occur most commonly in adults between the ages of 20 and 40. It is not currently known whether cluster headaches are more common in some racial or ethnic groups than in others; however, many patients with cluster headaches have a history of face or head trauma. The demographics of secondary headaches vary depending on the disease or disorder that causes the headache.

GALE ENCYCLOPEDIA OF NEUROLOGICAL DISORDERS

Analgesic A medication that relieves pain without causing loss of consciousness; over-the-counter analgesics include aspirin and NSAIDs. Aura A group of visual or other sensations that precedes the onset of a migraine attack. Cephalalgia The medical term for headache. Dura mater The outermost and toughest of the three membranes or meninges that cover the brain and spinal cord. The arteries that supply the dura mater and the portion of the dura mater at the base of the skull are sensitive to pain. Endodontist A dentist who specializes in the treatment of diseases and injuries that affect the tooth root, dental pulp, and the tissues surrounding the tooth root. Idiopathic Of unknown cause or spontaneous origin. Some headaches are considered idiopathic. Neurotransmitter Any of a group of chemicals that transmit nerve impulses across the gap (synapse) between two nerve cells. Nociceptor A specialized type of nerve cell that senses pain. Open-label study A type of study in which both the researchers and the subjects are aware of the drug or therapy that is being tested. Pathophysiology The changes in body functions associated with a disorder or disease. Primary headache A headache that is not caused by another disease or medical condition.

Prodrome A symptom or group of symptoms that appears shortly before an acute attack of illness. The term comes from a Greek word that means “running ahead of.” Projectile vomiting Forceful vomiting that is not preceded by nausea. It is usually associated with increased pressure inside the head. Prophylaxis A measure taken to prevent disease or an acute attack of a chronic disorder. Migraine prophylaxis refers to medications taken to reduce the frequency of migraine attacks. Rebound headache A type of primary headache caused by overuse of migraine medications or pain relievers. It is also known as analgesic abuse headache. Secondary headache A headache that is caused by another disease or disorder. Somatoform disorders A group of psychiatric disorders in the DSM-IV classification that are characterized by external physical symptoms or complaints related to psychological problems rather than organic illness. Spondylosis A general medical term for degenerative changes in the spinal vertebrae caused by osteoarthritis. Status migrainosus The medical term for an acute migraine headache that lasts 72 hours or longer. Temporomandibular joint (TMJ) The small joint in front of the ear in humans where the mandible (lower jaw) is attached to the skull.

Causes and symptoms

• the venous sinuses inside the head

Causes

• the large arteries at the base of the brain

PHYSICAL A person feels headache pain when specialized nerve endings known as nociceptors are stimulated by pressure on or injury to any of the pain-sensitive structures of the head. Most nociceptors in humans are located in the skin or in the walls of blood vessels and internal organs; the bones of the skull and the brain itself do not contain nociceptors.

The specific parts of the head that are sensitive to pain include: • the skin that covers the skull and cervical spine • the 5th, 9th, and 10th cranial nerves and the nerves that supply the upper part of the neck

• the large arteries that supply the dura mater, which is the outermost of the three meninges (membranes) that cover the brain and spinal cord • the portion of the dura mater at the base of the skull Tension headaches typically result from tightening of the muscles of the face, neck, and scalp as a result of emotional stress; physical postures that cause the head and neck muscles to tense (e.g., holding a phone against the ear with one’s shoulder); depression or anxiety; temporomandibular joint dysfunction (TMJ); or degenerative arthritis of the neck. The tense muscles put pressure on the walls of the blood vessels that supply the neck and head,

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Key Terms

Headache

which stimulates the nociceptors in the tissues that line the blood vessels. In addition, the nociceptors in patients with chronic tension headaches appear to be abnormally sensitive to stimulation.

• headache following a head injury that is not relieved by OTCs

The pathophysiology of migraine headaches has been debated among doctors since the 1940s. Some researchers think that migraines are the end result of a magnesium deficiency in the brain or of hypersensitivity to a neurotransmitter known as dopamine. Another theory holds that certain nerve cells in the brain cortex become unusually excitable and depolarize (lose their electrical potential) spontaneously, releasing potassium and glutamate, an amino acid. These substances then depolarize nearby nerve cells, resulting in a chain reaction known as corticalspreading depression (CSD). CSD then leads to changes in the amount of blood flowing through the blood vessels and stimulation of their nociceptors, resulting in severe headache. More recently, the discovery of specific genes associated with migraine indicates that genetic mutations are responsible for the abnormal excitability of the nerve cells in the brains of patients with migraine.

• persistent or violent vomiting

• headache triggered by exercise, coughing, sexual activity, or bending over • change in the character of the headaches—for example, persistent severe headaches in a person who has previously had only mild headaches of brief duration • recurrent headaches in a child • recurrent severe headaches, beginning after age 50

Diagnosis Patient history

Little is known about the causes of cluster headaches or changes in the central nervous system that produce them.

The differential diagnosis of headaches begins with a complete patient history, including a family history. In many cases, a primary care physician can make the diagnosis on the basis of the history. The doctor will ask the patient about head injuries or surgery on the head; eye problems or disorders; sinus infections; dental problems or extensive oral surgery; and medications that the patient is taking regularly.

PSYCHOLOGICAL Chronic headaches are often associated with anxiety, depression, or a specific group of mental disorders known as somatoform disorders. These disorders include hypochondriasis and pain disorder; they are characterized by physical symptoms (frequently headache) that suggest that the patient has a general medical condition, but there is no diagnosable disease or disorder that fully accounts for the patient’s symptoms. The relationship between psychological and physical factors in headaches is complex in that headaches may be either the cause or result of emotional disturbances, or both. Some patients find that chronic headaches disappear completely after a stressful family- or job-related situation has been resolved.

After taking the history, the doctor will ask the patient to describe the location and type of pain that he or she experiences during the headache. People who have tension headaches will typically describe the pain as “viselike,” “tightening,” “pressing,” or as a steady or constant ache. Patients with migraine headaches, on the other hand, will usually say that the pain has a “throbbing” or “pulsating” character, while patients with cluster headaches describe the pain as “penetrating” or “piercing.” About 85% of patients with tension headaches experience pain on both sides of the head, most commonly in the area around the forehead and temples. Patients with migraine or cluster headaches, however, are more likely to feel pain on only one side of the head.

Warning symptoms Most headaches are not associated with serious or life-threatening illnesses. Patients should, however, immediately call their primary physician if they have any of the following symptoms: • three or more headaches per week • need for a pain reliever every day or almost every day • need for greater than recommended doses of over-thecounter medications (OTCs) • stiff neck or fever accompanying the headache • shortness of breath, hearing problems, blurry vision, or severe sore throat • dizziness, weakness, slurred speech, mental confusion, or drowsiness 406

Some primary care physicians give the patient a printed questionnaire that consists of 50–55 brief yes/no questions that cover such matters as the timing and frequency of the headaches; whether other family members have the same type of headache; whether the patient feels depressed; whether the headaches are related to changes in the weather; and so on. The answers to the questions will usually fall into a pattern that tells the doctor whether the patient has migraines, tension headaches, cluster headaches, or headaches with other causes. The doctor may also ask the patient to keep a headache diary to help identify foods, stress, lack of sleep, weather, and other factors that may trigger headaches. It is possible for patients to have more than one type of headache. For example, patients with chronic tension headaches often have migraine headaches as well.

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prophylaxis (to prevent or lower the frequency of migraine attacks) include tricyclic antidepressants, beta-blockers, and anti-epileptic drugs, which are also known as anticonvulsants. As of 2003, sodium valproate (Epilim) is the only anticonvulsant approved by the Food and Drug Administration (FDA) for prevention of migraine. Such newer anticonvulsants as gabapentin (Neurontin) and topiramate (Topamax) are presently being evaluated as migraine preventives. Moreover, a new study reported that three drugs currently used to treat disorders of muscle tone are being explored as possible preventives for migraine— Botox, baclofen (Lioresal), and tizanidine (Zanaflex). Early results of open trials of these medications are positive.

Special studies Some laboratory tests are useful in identifying headaches caused by infections or by such disorders as anemia or thyroid disease. These tests include a complete blood count (CBC); erythrocyte sedimentation rate (ESR); and blood serum chemistry profile. Patients who report visual disturbances and other neurologic symptoms may be given visual field tests and have the pressure of the fluid inside their eyes (intraocular pressure) tested to check for glaucoma. A lumbar puncture (spinal tap) may be done to confirm a diagnosis of idiopathic intracranial hypertension. Imaging studies may include x rays of the sinuses to check for sinus infections; and CT or MRI scans, which are done to rule out brain tumors and cerebral aneurysms. Patients whose symptoms cannot be fully explained by the results of physical examinations and tests may be referred to a psychiatrist for evaluation of psychological factors related to their headaches.

Nonsteroidal anti-inflammatory drugs acetaminophen (Tylenol), ibuprofen (Motrin), and naproxen (Aleve) are helpful for early or mild migraines. More severe or unresponsive attacks may be treated with dihydroergotamine; a group of drugs known as triptans; beta-blockers and calcium channel-blockers; antiseizure drugs; antidepressants (SSRIs); meperidine (Demerol); or metoclopramide (Reglan). Some of these are also available as nasal sprays, intramuscular injections, or rectal suppositories for patients with severe vomiting. Sumatriptan and the other triptan drugs (zolmitriptan, rizatriptan, naratriptan, almotriptan, and frovatriptan) should not be taken by patients with vascular disease, however, because they cause narrowing of the coronary arteries.

Treatment Medical TENSION HEADACHES Episodic tension headaches

are usually relieved fairly rapidly by such over-the-counter analgesics as aspirin (300–600 mg every four hours), acetaminophen (650 mg every four hours), or another nonsteroidal anti-inflammatory drug (NSAID), usually ibuprofen (Advil) or naproxen (Naprosyn, Aleve). The doctor may prescribe a tricyclic antidepressant or benzodiazepine tranquilizer in addition to a pain reliever for patients with chronic tension headaches. A newer treatment for chronic tension headaches is botulinum toxin (Botox type A), which appears to work very well for some patients. As of 2003, however, Botox has not yet been evaluated in controlled multicenter studies as a treatment for chronic headaches; the data obtained so far are derived from case reports and open-label studies. MIGRAINE HEADACHES Medications can be prescribed to prevent migraines as well as to treat the symptoms of an acute attack. Drugs that are given for migraine

About 40% of all migraine attacks do not respond to treatment with triptans or any other medication. If the headache lasts longer than 72 hours—a condition known as status migrainosus—the patient may be given narcotic medications to bring on sleep and stop the attack. Patients with status migrainosus are often hospitalized because they are likely to be dehydrated from severe nausea and vomiting. CLUSTER HEADACHES Medications that are given as prophylaxis for cluster headaches include verapamil (Calan, Isoptin, Verelan), which is a calcium channel blocker, and methysergide (Sansert), which is a derivative of ergot. A new study indicates that topiramate (Topamax), an anticonvulsant, is also effective in preventing cluster headaches. Sumatriptan (Imitrex) or indomethacin (Indameth, Indocin) may be prescribed to suppress an attack. REBOUND HEADACHES Continued use of some pain relievers or antimigraine drugs can lead to rebound headaches, which may be frequent or chronic and often occur in the early morning hours. Rebound headache can be avoided by using antimigraine drugs or analgesics under a doctor’s supervision, using only the minimum dose necessary to treat symptoms. Tizanidine (Zanaflex) has been reported to be effective in treating rebound headaches when taken together with an NSAID; Botox has also been used successfully in some patients.

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Physical examination The physical examination helps the doctor identify other symptoms and signs that may be relevant to the diagnosis, such as fever; difficulty breathing; nausea or vomiting; stiff neck; changes in vision or hearing; watering or inflammation of the nose and eyes; evidence of head trauma; skin rashes or other indications of an infectious disease; and abnormalities in the structure or alignment of the patient’s spinal column, teeth or jaw. In some cases, the doctor may refer the patient to a dentist, oral surgeon, or endodontist for a more detailed evaluation of the patient’s mouth and jaw.

Headache

Diet and lifestyle modifications One measure that people can take to lower the risk of episodic tension headaches is to get enough sleep and eat nutritious meals at regular times. Skipping meals, using unbalanced fad diets to lose weight, and having insufficient or poor-quality sleep can bring on tension headaches. In fact, the common association of tension headaches with hunger, lack of sleep, heat, and sudden temperature extremes has led some researchers to suggest that headaches developed over the course of human evolution as an internal protective response to stress from the environment. Changes in diet may be helpful to some patients with migraine, although some experts think that the role of foods in triggering migraines has been exaggerated. Women with migraines, however, often benefit by switching from oral contraceptives to another method of birth control or by discontinuing estrogen replacement therapy. Patients with cluster headaches are advised to quit smoking and minimize their use of alcohol, because nicotine and alcohol appear to trigger cluster headaches. Currently, the precise connection between these chemicals and cluster attacks, however, is not completely understood. Surgical Headaches that are caused by brain tumors, post-injury hematomas, dental problems, or disorders affecting the spinal disks usually require surgical treatment. Surgery may also be used to treat cases of idiopathic intracranial hypertension that do not respond to treatment with steroids, repeated lumbar punctures, or weight reduction. Some plastic surgeons have reported success in treating patients with chronic migraines by removing some muscle tissue near the eyebrows, cutting a branch of the trigeminal nerve, and repositioning the soft tissue around the temples. Psychotherapy Psychotherapy may be helpful to patients with chronic headaches by interrupting the “feedback loop” between emotional upset and the physical symptoms of headaches. One type of psychotherapy that has been shown to be effective is cognitive restructuring, an approach that teaches people to reframe the problems in their lives—that is, to change their conscious attitudes and responses to these stressors. Some psychotherapists teach relaxation techniques, biofeedback, or other approaches to stress management as well as cognitive restructuring. Complementary and alternative (CAM) treatments There are a number of different CAM treatments for headache, but most fall into two major groups: those intended as prophylaxis or pain relief, and those that reduce the patient’s stress level. 408

CAM therapies intended to prevent headaches or relieve discomfort include: • Feverfew (Tanacetum parthenium). Feverfew is an herb related to the daisy that is traditionally used in England to prevent migraines. Published studies indicate that feverfew can reduce the frequency and intensity of migraines. It does not, however, relieve pain once the headache has begun. • Butterbur root (Petasites hybridus). Petadolex is a natural preparation made from butterbur root that has been sold in Germany since the 1970s as a migraine preventive. Petadolex has been available in the United States since December 1998. • Brahmi (Bacopa monnieri). Brahmi is a herb used in Ayurvedic medicine to treat headaches related to anxiety. • Acupuncture. Studies funded by the National Center for Complementary and Alternative Medicine (NCCAM) have found that acupuncture is an effective treatment for headache pain in many patients. • Naturopathy. Naturopaths include dietary advice and nutritional therapy in their approach to treatment, which is often effective for patients with episodic or chronic tension headaches. • Chiropractic. Some patients with tension or migraine headaches find spinal manipulation effective in relieving their pain; however, no controlled studies of the longterm effectiveness of chiropractic in treating headaches have been done as of 2003. CAM therapies that are reported to be effective in reducing emotional stress related to headaches include: • yoga and t’ai chi • prayer and meditation • aromatherapy • hydrotherapy, particularly whirlpool baths • Swedish massage and shiatsu • pet therapy • humor therapy • music therapy

Clinical trials As of late 2003, there were three National Institutes of Health (NIH) trials recruiting patients with headaches: a study evaluating a new intranasal drug (civamide) for cluster headaches; a study of the effectiveness of biofeedback and relaxation training in patients with chronic migraine or tension headaches; and a study of migraine headaches in children.

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The prognosis of primary headaches varies. Episodic tension headaches usually resolve completely in less than a day without affecting the patient’s overall health. According to NIH statistics, 90% of patients with chronic tension or cluster headaches can be helped. The prognosis for patients with migraines, however, depends on whether the patient has one or more of the other disorders that are associated with migraine. These disorders include Tourette’s syndrome, epilepsy, ischemic stroke, hereditary essential tremor, depression, anxiety, and others. For example, migraine with aura increases a person’s risk of ischemic stroke by a factor of six. The prognosis of secondary headaches depends on the seriousness and severity of their cause. Resources BOOKS

American Psychiatric Association. Diagnostic and Statistical Manual of Mental Disorders, 4th edition, text revision. Washington, DC: American Psychiatric Association, 2000. “Headache.” The Merck Manual of Diagnosis and Therapy. Edited by Mark H. Beers and Robert Berkow. Whitehouse Station, NJ: Merck Research Laboratories, 2002. Pelletier, Kenneth R. The Best Alternative Medicine, Part II, “CAM Therapies for Specific Conditions: Headache.” New York: Simon & Schuster, 2002. “Psychogenic Pain Syndromes.” The Merck Manual of Diagnosis and Therapy. Edited by Mark H. Beers and Robert Berkow. Whitehouse Station, NJ: Merck Research Laboratories, 2002. PERIODICALS

Argoff, C. E. “The Use of Botulinum Toxins for Chronic Pain and Headaches.” Current Treatment Options in Neurology 5 (November 2003): 483–492. Astin, J. A., and E. Ernst. “The Effectiveness of Spinal Manipulation for the Treatment of Headache Disorders: A Systematic Review of Randomized Clinical Trials.” Cephalalgia 22 (October 2002): 617–623. Corbo, J. “The Role of Anticonvulsants in Preventive Migraine Therapy.” Current Pain and Headache Reports 7 (February 2003): 63–66. Freitag, F. G. “Preventative Treatment for Migraine and Tension-Type Headaches: Do Drugs Having Effects on Muscle Spasm and Tone Have a Role?” CNS Drugs 17 (2003): 373–381. Guyuron, B., T. Tucker, and J. Davis. “Surgical Treatment of Migraine Headaches.” Plastic and Reconstructive Surgery 109 (June 2002): 2183–2189. Headache Classification Subcommittee of the International Headache Society. “The International Classification of Headache Disorders,” 2nd ed. Cephalalgia 24 (2004) (Supplement 1): 1–150. Lainez, M. J., J. Pascual, A. M. Pascual, et al. “Topiramate in the Prophylactic Treatment of Cluster Headache.” Headache 43 (July-August 2003): 784–789.

Lenaerts, M. E. “Cluster Headaches and Cluster Variants.” Current Treatment Options in Neurology 5 (November 2003): 455–466. Lipton, R. B., A. I. Scher, T. J. Steiner, et al. “Patterns of Health Care Utilization for Migraine in England and in the United States.” Neurology 60 (February 11, 2003): 441–448. Marconi, R., M. De Fusco, P. Aridon, et al. “Familial Hemiplegic Migraine Type 2 is Linked to 0.9Mb Region on Chromosome 1q23.” Annals of Neurology 53 (March 2003): 376–381. Mendizabai, Jorge, MD. “Cluster Headache.” eMedicine, 26 September 2003. . Sahai, Soma, MD, Robert Cowan, MD, and David Y. Ko, MD. “Pathophysiology and Treatment of Migraine and Related Headache.” eMedicine, April 30, 2002 (February 16, 2004). . Singh, Manish K., MD. “Muscle Contraction Tension Headache.” eMedicine, October 5, 2001 (February 16, 2004). . Soragna, D., A. Vettori, G. Carraro, et al. “A Locus for Migraine Without Aura Maps on Chromosome 14q21.2–q22.3.” American Journal of Human Genetics 72 (January 2003): 161–167. Tepper, S. J., and D. Millson. “Safety Profile of the Triptans.” Expert Opinion on Drug Safety 2 (March 2003): 123–132. OTHER

Migraine Information Page. NINDS. 2003 (February 16, 2004). . National Institute of Neurological Disorders and Stroke (NINDS). “Headache—Hope Through Research.” Bethesda, MD: NINDS, 2001. (February 16, 2004.) . ORGANIZATIONS

American Academy of Neurology (AAN). 1080 Montreal Avenue, Saint Paul, MN 55116. (651) 695-2717 or (800) 879-1960; Fax: (651) 695-2791. memberservices@ aan.com. . American Council for Headache Education (ACHE). 19 Mantua Road, Mt. Royal, NJ 08061. (856) 423-0258; Fax: (856) 423-0082. [email protected]. . International Headache Society (IHS). Oakwood, 9 Willowmead Drive, Prestbury, Cheshire SK10 4BU, United Kingdom. +44 (0) 1625 828663; Fax: +44 (0) 1625 828494. [email protected]. . National Headache Foundation. 820 North Orleans, Suite 217, Chicago, IL 60610. (773) 525-7357 or (888) NHF-5552. . NIH Neurological Institute. P. O. Box 5801, Bethesda, MD 20824. (301) 496-5751 or (800) 352-9424. .

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Prognosis

Hearing disorders

❙ Hearing disorders Definition

Hearing disorders range from a temporary, partial loss of hearing to the permanent loss of hearing known as deafness.

Description The variety of hearing disorders includes a loss or decrease in the ability to discern certain frequencies of sound, a ringing or other noise that is unrelated to any actual external sound, damage due to physical trauma or infection, and genetically determined structural malformation.

Demographics Hearing disorders occur worldwide in all races. The hearing loss that occurs with age is very common, affecting an estimated 30% of Americans over 60 years of age and 50% of those older than 75. Tinnitus, a ringing or noisy sensation in the ears, is quite common with an estimated 20% of people affected worldwide. In the United States alone, some 36 million people experience tinnitus. For hearing loss caused by otosclerosis, middle-aged Caucasian women are more prone than others, perhaps as a consequence of hormonal changes. In otosclerosis, abnormal bone development occurs in the middle ear, resulting in progressive hearing loss. Sudden hearing loss happens more often to people ages 30–60 for unknown reasons.

Conductive hearing loss In conductive hearing loss, sound is not transmitted efficiently through the outer and middle ears. These regions house the eardrum, ear canal, and the trio of tiny bones (ossicles) in the middle ear that transmits sound energy to the inner ear. The hearing loss can be due to malformation of structures like the canal or the ossicles, dense buildup of ear wax, or fluid in the ear due to colds, allergies, or infections like otitis media. Symptoms include a decreased ability to detect fainter sounds and a general lowering of the sound level that can be detected. Otitis media Otitis media is an inflammation in the middle ear that is usually accompanied by fluid buildup. The condition may be transient in some children, but persistent in others to the point of requiring surgical correction. In developed countries, otitis media is second to the common cold as the most common health problem in preschool-aged children. Hearing loss occurs because of the fluid accumulation and the resulting suppression of sound waves moving to the inner ear. Central auditory processing disorders Central auditory processing disorders result in hearing loss when the areas of the brain involved in hearing are damaged. Sources of damage include disease, injury, and tumor growth. Consistent with the variety of causes, the symptoms of the disorders include the inability to hear certain sounds, inability to tell one sound from another, and the inability to recognize a pattern such as speech in sounds.

Causes and symptoms Presbycusis Presbycusis (or sensorineural hearing loss) is the loss of hearing that occurs with age. The condition results from the long-term assault on the ear structures, particularly on the inner ear, from a lifetime of noise, ear infections, or growths on bones of the outer or middle ear. The inner ear is where the vibrational sound waves are converted to electrical signals, courtesy of thousands of tiny hairs that are in a fluid-enclosed space called the cochlea. The hairs are connected to nerve cells, which send the electrical signals to the brain. Most age-related hearing loss is due to damage to the cochlea. The tiny hairs can bend or even break, and the attached nerve cells can degenerate. The resulting less-efficient transmission of the electrical signal, particularly of higher-pitched tones, causes hearing loss. Symptoms of presbycusis typically include increased difficulty in making out sounds of a certain volume or tone, especially when background sounds are present. 410

Congenital hearing loss Congenital hearing loss is present from birth and is caused by a genetic defect or disturbance during fetal development. Genetic factors cause more than half of all such disorders. Depending on the nature of the genetic defect, the occurrence of the hearing loss may be common or rare. For example, if both parents have a genetically determined hearing deficiency, the chance of passing the trait to their children is high. In other cases, people who have normal hearing carry a second, defective copy of a crucial gene. The chance of passing on the hearing loss is 25%. Hearing loss at birth can also be caused by pre-birth infections such as measles, cytomegalovirus, or herpes simplex virus. Otosclerosis The abnormal growth of the bone of the middle ear prevents the ossicles, particularly the last of the trio of bones (the stapes), from properly transmitting sound

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Cochlear implant A device used for treating deafness that consists of one or more electrodes surgically implanted inside or outside the cochlea, an organ in the inner ear that transforms sound vibrations in the inner ear into nerve impulses for transmission to the brain. Ossicles Tiny bones in the middle ear, the incus, malleus, and stapes, that convey sound impulses from the eardrum to the inner ear. Otitis media Inflammation, usually with infection, of the middle ear. Otosclerosis Abnormal bone development in the middle ear, resulting in progressive hearing loss. Presbycusis Loss of hearing that gradually occurs because of age-related changes in the inner or middle ear. Tinnitus Ringing or noisy sensations in the ears when no external sound is present, often associated with hearing impairment and excess noise exposure.

waves to the inner ear in otosclerosis. The cause(s) of otosclerosis are not clear, although observations that the disorder spans family generations make a genetic source likely. The diminished hearing that occurs is not sudden. Rather, the change is gradual and is usually recognized when the person becomes aware that she or he can no longer hear a low-pitched sound such as a whisper. Other genetically based hearing losses Usher syndrome affects both the ears and eyes. The defective genes that are at the heart of the malady are passed from parents to children. Depending on the nature of the syndrome, children can be born with moderate to severe hearing loss, or can be totally deaf. Others begin life essentially normal, with hearing loss progressively worsening to deafness by the teenage years. Waardenburg syndrome affects both the ears and the color of the skin, eyes, or hair. Eyes can be different colors and hair can have a patch of white or become prematurely gray. Hearing can range from normal to severely impaired. At least four genes can produce the syndrome when they undergo mutation. Ménière’s disease Ménière’s disease is a change in the volume of the inner ear that produces swelling, pressure, pain, intermittent hearing loss, dizziness, and tinnitus. Swelling may be

Tinnitus Tinnitus is a ringing noise or other sound that occurs in the absence of an external source of sound. For some, tinnitus is an infrequent occurrence. Others are very inconvenienced by near-constant tinnitus. The noises experienced in tinnitus range in description and include electronic noise, hissing steam, chirping crickets, bells, breaking glass, buzzing, and even the noise of a chainsaw. The noises can be constant or may rise and fall in volume with head motion or with the planting of feet during running. Tinnitus has various known triggers. Foods such as red wine, cheese, and chocolate have been implicated. Over-the-counter drugs such as ibuprofen and extrastrength aspirin, and prescribed drugs, including oral contraceptives and aminoglycoside antibiotics, can cause tinnitus. Drug-related tinnitus disappears when the dosage is reduced or the drug stopped. The growth of certain tumors can cause tinnitus. The aging of the inner ear is also a factor in tinnitus. As nerve cells deteriorate and the many hairs in the cochlea that transmit sound waves to the nerves become damaged and broken with time, the signaling of sound impulses to the brain becomes faulty. Nerves may fire when there has been no stimulus. The brain interprets the signal as actual noise. Sudden deafness or sudden sensorineural hearing loss This rapid decrease or complete loss of hearing can occur within minutes or over the course of several days. The hearing loss typically affects one ear and often resolves with time. Sudden deafness is much more serious and should be treated as a medical emergency requiring immediate medical attention. Causes are unclear and may involve an infection, head injury, reaction to a drug, problems with circulation, and other disorders such as multiple sclerosis. Deafness The complete loss of hearing can be due to genetically determined developmental difficulties, a trauma such as a loud noise, physical damage to structures in the ear, nerves, or relevant areas of the brain, and infection during pregnancy (such as rubella). In a great many cases, deafness is permanent. Childhood deafness typically becomes apparent when a child appears inattentive and fails to meet language milestones.

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Key Terms

so pronounced that membranes like the eardrum can rupture. As well, some people report that their voice sounds louder than normal. The disease may be caused by a viral or bacterial infection.

Hearing disorders A mother and young daughter communicate with sign language. (© Custom Medical Stock Photo. Reproduced by permission.)

Diagnosis

Treatment

Presbycusis is usually first detected by a family physician. Diagnosis is subsequently made by a hearing specialist or an audiologist, and involves a hearing test in which sounds of differing frequencies and gradually decreasing volume are sent to one ear at a time. Tinnitus is self-evident, as the ringing or other sensation is impossible to ignore. In contrast, otitis media can be difficult to diagnose, as it is often not accompanied by pain or a fever. Fluid in the ear can be a sign of otitis media. Also, changes in children’s behavior such as playing the television louder, misunderstanding directions, and pulling at the ears can all be indicators of otitis media. Imaging of the inside of the ear using the technique of magnetic resonance imaging (MRI) can be useful in diagnosing Ménière’s disease. Usher syndrome is diagnosed by the simultaneous appearance of ear and eye problems.

Treatment team The varied treatment can involve the family physician and more specialized doctors, including audiologists and otolaryngologists (specialists in ear, nose, and throat disorders). As well, speech-language pathologists can be involved in the treatment of hearing loss-related speech disorders in children. 412

Treatment for presbycusis can be as simple as keeping the ear canals free from sound-muffling wax buildup. Another fairly common treatment for older people is the use of a hearing aid, which amplifies sound and directs the sound into the ear canal. About 20% of those with age-related hearing loss can benefit from an aid. More severe presbycusis can be treated using a cochlear implant. The device actually compensates for the nonworking parts of the inner ear. Conductive hearing loss can usually be fully corrected by medication or surgery. Similarly, when tinnitus is caused by overmedication, the condition is alleviated by modifying or eliminating the dosage of the drug. Ménière’s disease and Usher syndrome cannot be cured, however, the symptoms can be greatly relieved by release of the buildup of pressure in the inner ear and the use of hearing aids or implants, respectively. Coping strategies and increased knowledge of the conditions can then help a person lead an essentially normal life. Otosclerosis that is more pronounced can be treated by a surgical procedure called a stapedectomy, in which the damaged portion of the middle ear, the stapes, one of the three bones of the middle ear, is bypassed by an implanted device that routes sound to the inner ear. Milder otosclerosis may be lessened by the use of a hearing aid.

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Some conditions that can be addressed by surgery or the use of a hearing aid or an implant have varying levels of recovery. Other conditions involving permanent deafness cannot be cured.

Clinical trials As of April 2004, at least eight clinical trials were active in the United States. Most focus on deafness, in particular the determination of the genetic factors that contribute to or cause deafness. Updated information on these studies can be found at the National Institutes of Health Web site for clinical trials at .

Prognosis Age-related hearing loss can be partially or almost completely compensated for by a change in lifestyle and the development of coping skills (listening to the radio at higher volume, different conversational behavior in crowds, use of hearing aids or implants). Otitis media can cause delayed speech development, if undiagnosed, because of the child’s impaired ability to hear. Sudden hearing loss usually resolves on its own within a few days to several weeks. However, in about 15% of cases, the condition worsens with time.

OTHER

“Hearing Loss.” MayoClinic.com. April 8, 2004 (May 30, 2004). . “Tinnitus.” MayoClinic.com. April 8, 2004 (May 30, 2004). . ORGANIZATIONS

American Academy of Audiology. 8300 Greensboro Drive, Suite 750, McLean, VA 22102. (703) 790-8466 or (800) 222-2336; Fax: (703) 790-8631. [email protected]. . American Speech-Language-Hearing Association. 10801 Rockville Pike, Rockville, MD 20852. (301) 638-8255 or (800) 638-8255; Fax: (301) 571-0457. actioncenter@ asha.org. . American Tinnitus Association. PO Box 5, Portland, OR 97207-0005. (503) 248-9985 or (800) 634-8978; Fax: (503) 248-0024. [email protected]. . Deafness Research Foundation. 1050 17th Street NW, Suite 701, Washington, DC 20036. (202) 289-5850. . National Center on Deafness. 18111 Nordhoff Street, Northridge, CA 91330-8267. (818) 677-2145; Fax: (818) 677-7693. [email protected]. . National Institute on Deafness and Other Communication Disorders, National Institutes of Health. 31 Center Drive, MSC 2320, Bethesda, MD 20892-2320. (301) 496-7243 or (800) 241-1044; Fax: (301) 402-0018. [email protected]. .

Brian Douglas Hoyle, PhD

Special concerns The various surgeries that can be performed all carry some risk, and the quality of sound that is provided by cochlear implants varies greatly among recipients. Additionally, tinnitus can be caused by the buildup of cholesterol in arteries around the ear, high blood pressure, and by malformed arteries or veins. Tinnitus, therefore, may be an indication of a more serious health problem. Resources

❙ Hemianopsia Definition

Hemianopsia is a term that describes a loss of vision that affects half of the visual field of one eye or both eyes.

BOOKS

Dugan, Marcia B. Living with Hearing Loss. Baltimore: Gallaudet Press, 2003. Schwartz, Sue. Choices in Deafness: A Parents’ Guide to Communication Options. Bethesda, MD: Woodbine House, 2003.

Description Hemianopsia prevents an individual from seeing objects in half of the visual field of a particular eye. As a result, an individual suffering from hemianopsia will not see objects that are in the affected visual field.

PERIODICALS

DeJonckere, P. H., and G. G. de Surgeres. “Acute Tinnitus and Permanent Audiovestibular Damage after Hepatitis B Vaccination.” International Tinnitus Journal (July 2001): 59–61. Waddell, A., and R. Canter. “Tinnitus.” American Family Physician (February 2004): 591–592.

Causes and symptoms Conditions or injuries that affect the optic nerve can cause hemianopsia. The sequelae (aftereffects) of stroke, brain aneurysm, occlusion of the optic artery, brain tumors, or traumatic head injuries can all result in hemianopsia. Occasionally, individuals who suffer from

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Recovery and rehabilitation

Hemifacial spasm

migraine headaches may experience hemianopsia during a migrainous episode or as part of the prodromal aura that precedes the actual headache; this type of hemianopsia resolves completely upon resolution of the headache. Transient hemianopsia can result from bouts of extremely high blood pressure (as occurs in eclampsia) or during or after a seizure. Other rare causes of hemianopsia include infections, such as encephalitis, brain abscess, progressive multifocal leukoencephalopathy, and CreutzfeldtJakob disease. Symptoms of hemianopsia involve the inability to see objects in half of the visual field of one or both eyes, which may be manifested by reading difficulties, problems walking through crowded areas, frequent accidents (bumping into objects that are located in the lost visual field), or being startled at what seems to be the sudden emergence of people or objects in the visual field.

Driving can be a particular concern for people with hemianopsia. By learning new techniques for scanning the environment, some individuals can safely return to driving; others will not be able to drive safely, and will no longer be able to obtain a driver’s license. This can result in significant changes in an individual’s lifestyle, independence, and employability. Resources BOOKS

Liu, Grant T., and Nancy J. Newman. “Cranial Nerve II and Afferent Visual Pathways.” In Textbook of Clinical Neurology, edited by Christopher G. Goetz. Philadelphia: W. B. Saunders Company, 2003. Pulsinelli, William A. “Ischemic Cerebrovascular Disease.” In Cecil Textbook of Internal Medicine, edited by Lee Goldman, et al. Philadelphia: W. B. Saunders Company, 2000. ORGANIZATIONS

Diagnosis Diagnosis is usually evident when basic testing reveals a blind area in half of the visual field of one or both eyes. Further testing will be necessary to uncover the underlying causative condition: CT or MRI scanning may reveal the presence of a stroke, aneurysm, or brain tumor.

Treatment team Neurologists, ophthalmologists, and neuroophthalmologists all work with patients with hemianopsia. Occupational therapists and vision rehabilitation specialists can be integral in teaching the individual how to compensate for their vision loss.

Treatment Treatment includes therapy to practice techniques that may help an individual overcome the obstacles of hemianopsia. For example, changing reading techniques (looking at the last part of the word, rather than the first) may improve an individual’s ability to read and enjoy reading. Special scanning techniques may be taught, using a machine called a Dynavision, which will help an individual learn how to turn the head in certain ways to scan the environment and compensate for the lost visual field. Special glasses lenses, some with mirrors or prisms incorporated, may allow an individual with hemianopsia to view a greater visual field.

Lighthouse International. 111 East 59th Street, New York, NY 10022. 212-821-9200 or 800-829-0500. info@ lighthouse.org. .

Rosalyn Carson-DeWitt, MD

❙ Hemifacial spasm Definition

A hemifacial spasm is an involuntary contraction of the muscles of facial expression, resulting in eyelid closure and upturning of the corner of the mouth and accompanied by facial weakness.

Description Hemifacial spasm results in involuntary contraction of the facial muscles limited to one side of the face. The eyelids are involved, and upturning of the corner of the mouth is observed. The patient may have facial twitching during periods of sleep. If left untreated, the twitching may worsen and extend to other facial muscles.

Demographics Females are affected more than males, regardless of race. Typically, patients afflicted with hemifacial spasm are in their 40s or 50s.

Causes and symptoms

Prognosis Recovery of vision after stroke or head injury is usually maximal within the first three to six months; hemianopsia persisting after that point is usually permanent. 414

Special concerns

The cause of hemifacial spasm has been linked to overactivity of the seventh cranial nerve nucleus that signals facial muscle movement. In other instances, hemifacial spasm may be caused by compression by a mass or

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Patients will usually report involuntary twitching of one side of the face (hemifacial), lasting seconds to minutes. Family members may observe facial twitching while the patient sleeps. Pain or numbness is usually not reported.

Diagnosis When a clinical diagnosis has been established, imaging of the brain is required to rule out ischemia, mass lesions, or abnormal vasculature. Magnetic resonance imaging (MRI) of the brain, with and without contrast, as well as MRI-angiography, are advised. Blood tests are not required for patients believed to have hemifacial spasm.

Treatment team Ophthalmologists, neuro-ophthalmologists, and neurologists are physicians who can diagnose and treat hemifacial spasm. If surgery is indicated as a form of treatment, it is usually performed by a neurological surgeon.

Treatment The mainstay of treatment is injection of botulinum toxin to the face, which results in temporary paralysis of selected muscles of facial expression. Botulinum toxin, commonly known as Botox (Allergen Inc.), is a neurotoxin produced by the bacterium, Clostridium botulinum. This toxin weakens facial muscles by inhibiting the release of a neurotransmitter, acetylcholine, which results in temporary and partial muscle paralysis. Botulinum toxin has become an accepted and widely used treatment for hemifacial spasm. Although its use is relatively safe and easily injected, the effect of botulinum toxin is temporary, lasting approximately six months. This necessitates the need for re-injection or increased doses of the toxin, depending on the patient’s response. If botulinum toxin fails to be effective or the patient does not tolerate it well, decompression of the seventh cranial nerve can be attempted. This procedure, performed by a neurosurgeon, entails placing a sponge between the seventh nerve and the vessel compressing the nerve. Other treatment options include severing branches of the seventh nerve, destruction of eyelid and facial musculature, and oral anti-seizure medications. However, oral medications have proven to be limited in their efficacy and have significant side effects.

Recovery and rehabilitation There is usually no recovery period following the injection of botulinum toxin. The maximal effects are usually seen four to seven days following injection.

Clinical trials Currently there are no clinical trials scheduled to study this disorder.

Prognosis The vast majority of patients responds favorably to injections with a low rate of complications. A small percentage of patients improves spontaneously, and benefits from psychotherapy, surgery, or oral medications.

Special concerns Support groups and information for patients and families are excellent resources that may improve treatment outcomes and psychosocial ramifications. Resources BOOKS

Beers, Mark H., and Robert Berkow, editors. “Cranial Nerve Disorders.” The Merck Manual of Diagnosis and Therapy. Whitehouse Station, NJ: Merck Research Laboratories, 1999. Burde, Ronald M., Peter J. Savino, and Jonathan D. Trobe. Clinical Decisions in Neuro-Ophthalmology, 3rd ed. St. Louis, MO: Mosby, 2002. Liu, Grant T., Nicholas J. Volpe, and Steven L. Galetta. NeuroOphthalmology Diagnosis and Management, 1st ed. Philadelphia: W.B. Saunders Company, 2001. OTHER

Gulevich, Steven. Hemifacial Spasm. . Cohen, Adam J., and M. Mercandetti. Oculopfacial Applications of Botulinum Toxin. . ORGANIZATIONS

Hemifacial Spasm Association. .

Adam J. Cohen, MD

Hemiplegia alterans see Alternating hemiplegia

❙ Hereditary spastic paraplegia Definition

Hereditary spastic paraplegia (HSP) is a hereditary degenerative disorder affecting the corticospinal tracts (long never fibers that supply the upper and lower limbs)

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abnormal blood vessel or by a lack of blood supply (ischemia) of the seventh cranial nerve at its origin or by the nucleus itself. It is thought that compression by a convoluted cerebral artery is the most common cause. In some patients, no underlying cause can be detected, which is termed an idiopathic hemifacial spasm. In younger patients, multiple sclerosis may be the cause.

Hereditary spastic paraplegia

within the spinal cord. The disease frequently results in progressive spasticity (involuntary movement) of leg muscles with varying degrees of stiffness and weakness of other muscle groups in the thighs, lumbar spinal area, and muscles responsible for up and down feet movements. The extent of degeneration and severity of symptoms varies among the affected people, even those among the same family group. The age of onset for the disease also varies. Some families show a pattern of disease, with symptoms developing earlier in each new generation. In most individuals, however, the disease onset occurs between the second and the fourth decades of life, with a few cases beginning later, or as early as infancy and early childhood.

Description Other names of this disorder are hereditary spastic paraparesis, Strumpell-Lorrain syndrome, Strumpell disease, familial spastic paraparesis, spastic spinal familial paralysis, and Troyer syndrome. When the only manifested symptom is progressive spasticity, HSP is also known as Pure Hereditary Spastic Paraplegia. HSP presents three forms of inheritance: autosomal dominant HSP, autosomal recessive HSP, and X-linked HSP. Autosomal dominant HSP requires the presence of an inherited mutation in only one copy of the gene responsible for the disease, whereas autosomal recessive HSP requires mutation in the two copies (maternal and paternal) to manifest the disease. X-linked HSP is rare and the mutated gene is located in the X chromosome, which is transmitted by the mother. HSP is also divided into two categories, uncomplicated HSP and complicated HSP.

Demographics As usually happens with other rare neurological diseases, the HSP symptoms may overlap or be mistaken with other neurodegenerative disorders. Consequently, HSP incidence is only estimated, with approximately three cases out of 100,000 individuals as an average estimate for the United States and Europe. Ninety percent of HSP cases are uncomplicated and do not affect life expectancy.

Causes and symptoms Hereditary spastic paraplegia (HSP) belongs to a group of neurodegenerative (progressive nervous system dysfunction) disorders with common symptoms of progressive and usually severe weakness and spasticity of the lower limbs. However, mutations in different genes may result in HSP, a phenomenon known as genetic heterogeneity. For instance, uncomplicated HSP may be inherited as an autosomal dominant mutation in about 70% of cases; but the involved mutated gene may be a different one, located in a different chromosome, from one family 416

Key Terms Ataxia A condition marked by impaired muscular coordination, most frequently resulting from disorders in the brain or spinal cord. Autosomal Relating to any chromosome besides the X and Y sex chromosomes. Human cells contain 22 pairs of autosomes and one pair of sex chromosomes. Corticospinal tract A tract of nerve cells that carries motor commands from the brain to the spinal cord. Neurodegenerative disease A disease in which the nervous system progressively and irreversibly deteriorates. Neuropathy A disease or abnormality of the peripheral nerves (the nerves outside the brain and spinal cord). Major symptoms include weakness, numbness, paralysis, or pain in the affected area. Spinal cord The elongated nerve bundles that lie in the spinal canal and from which the spinal nerves emerge.

to another. Any of these genes is generically known as spastic paraplegia gene or SPG. SPGs responsible for the uncomplicated form of the disease have been identified in chromosomes 2, 8, 12, 14, 15, 19, and 20; and an autosomal dominant complicated HSP gene has been found in chromosome 10. Autosomal recessive HSP may be caused by other than the abovementioned SPGs, also located either in chromosome 8 or 15, or yet in chromosome 16. One form of autosomal recessive HSP, the Troyer syndrome, is associated with a SPG located in chromosome 13. Two different genes associated with autosomal recessive HSP have also been identified on the X chromosome. Approximately 40–50% of all cases of autosomal dominant HSP are caused by SPG located on chromosome 2. Uncomplicated autosomal dominant HSP may start at any phase of life, from infancy or early childhood to adulthood or old age. In children, uncomplicated HSP progresses until adolescence and then stabilizes, resulting in partial walking disability. However, complete paralysis of the legs is rare in uncomplicated HSP, whatever the age of onset. Autosomal recessive HSP is the complicated form of the disease with onset between two and 16 years of age. Complicated HSP symptoms continually progress and

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(6682); Fax: (212) 875-8389. [email protected]. .

Sandra Galeotti

Heredopathia atactica polyneuritiform see Refsum disease Herpes zoster see Shingles Hirayama syndrome see Monomelic amyotrophy

Diagnosis Family clinical history and physical and neurological examinations are the first tools in HSP diagnosis. The physician will conduct comparative examination of muscle tone and strength between arms and legs and look for signs of weakness in specific muscle groups of the thigh, presence of abnormal increase of deep tendon brisk reflexes in the lower extremities, loss of ankle flexibility, and decrease of sensation in the lower extremities. Genetic screening for SPG is the definitive test to avoid misdiagnosis.

Treatment There is no curable or preventive treatment for HSP, except for antispasmodic drugs to reduce muscle spasms. However, symptomatic treatment for sensitive neuropathy may also be necessary in recessive HSP. Supportive care includes physical therapy and devices to assist with walking. Resources BOOKS

Fenichel, Gerald M. Clinical Pediatric Neurology: A Signs and Symptoms Approach, 4th ed. Philadelphia: W. B. Saunders Company, 2001. ORGANIZATIONS

Genetic Alliance. 4301 Connecticut Avenue, N.W., Suite 404, Washington, DC 20008-2369. (202) 966-5557 or (800) 336-GENE (4363); Fax: (202) 966-8553. [email protected]. . National Ataxia Foundation (NAF). 2600 Fernbrook Lane, Suite 119, Minneapolis, MN 55447-4752. (763) 5530020; Fax: (763) 553-0167. [email protected]. . Spastic Paraplegia Foundation. P.O. Box 1208, Forston, GA 31808. (978) 256-2673. [email protected]. . Worldwide Education & Awareness for Movement Disorders (WE MOVE). 204 West 84th Street, New York, NY 10024. (212) 875-8312 or (800) 437-MOV2

❙ Holoprosencephaly Definition

Holoprosencephaly is a birth defect caused by failure of the forebrain (prosencephalon) to grow as two separate hemispheres in the first few weeks of fetal life. The more complete the failure to divide, the worse the resulting abnormalities of brain, skull, and face. In its most severe form, holoprosencephaly entails the development of a tiny, undivided forebrain and is fatal before birth. Equivalent terms are arhinencephaly, holotelencephaly, and telencephalosynapsis. The prefix holo means undivided.

Description There are three degrees of severity of holoprosencephaly: (1) alobar holoprosencephaly, in which a tiny, single-lobed, nonfunctional forebrain brain develops, along with other severe cerebral abnormalities and severe facial deformities including cyclopism, or formation of a single, nonfunctional eye where the bridge of the nose should be; (2) semilobar holoprosencephaly, in which the brain is partly divided and there may be significant facial deformities such as cleft palate; and (3) lobar holoprosencephaly, in which the brain is partly divided, but there is some fusion of structures along the midline. Some authorities distinguish a fourth category to include various mild abnormalities of prosencephalic division, namely olfactory aplasia (absence of olfactory bulbs and tracts) and middle interhemispheric variant, in which the posterior frontal and parietal lobes of the brain are not well-separated.

Demographics Holoprosencephaly occurs in a small number of live births, with estimates varying from one in 5,000 to one in 31,000. However, its actual incidence is much higher, since many fetuses with holoprosencephaly, approximately 97%, are either stillborn or spontaneously aborted (miscarried). The rate of holoprosencephaly among all

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may be associated with other neurological conditions, such as epilepsy, mental retardation, peripheral neuropathy (numbness, pain, and sensory changes in nerves of limb extremities), ocular (eye) degenerations, such as retinopathy and/or the destruction of optic nerve tissues (ocular neuropathy). Other clinical complications are ataxia (motor coordination disorders), dysarthria (speech disorders), nystagmus (repetitive and involuntary eye movements), and ichthyosis (abnormal dryness, scaling, and thickening of the skin). However, these neurological symptoms may be caused by other disorders present at the same time. For instance, a person with uncomplicated HSP may have peripheral neuropathy due to diabetes.

Holoprosencephaly MRI of a 20-month-old girl with holoprosencephaly. The dark area represents the abnormally large fluid-filled ventrical typical of this disease. (Simon Fraser / Neuroradiology Dept. / Newcastle General Hospital / Science Photo Library.)

pregnancies may therefore be as high as 1:200 or 1:250. As of 2004, the medical literature did not note a higher prevalence of holoprosencephaly in any particular racial group or geographic area.

Causes and symptoms Holoprosencephaly has no single cause, but about half of all cases are associated with abnormal karyotype (abnormal numbers of chromosomes), especially trisomy 13 (extra copy of chromosome 13) and trisomy 15 (extra copy of chromosome 15). It can also run in families as an autosomal dominant, autosomal recessive, or X-linked recessive trait. Currently, researchers believe that holoprosencephaly might be linked to as many as 12 chromosomal regions on 11 chromosomes. Risk is increased if the mother has diabetes or has an infection during pregnancy such as syphilis, herpes, cytomegalovirus, rubella, or toxoplasmosis. Use of certain drugs or other substances during pregnancy (e.g., alcohol, aspirin, lithium, thorazine, anticonvulsants, hormones, retinoic acid) has also been suggested as a risk factor. Women who have had previous miscarriages and bleeding in the first trimester are also more likely to have fetuses with holoprosencephaly. 418

MRI of a brain with holoprosencephaly. The red area represents the large, fluid-filled cavity that develops where the forebrain would normally be. (Mehau Kulyk / Photo Researchers, Inc.)

Alobar holoprosencephaly causes death, either before or soon after birth. Cyclopia or formation of a single eye often occurs, with the nose being absent, having only a single nostril, or being replaced by a proboscis (small, tubular nose) either above or below the eye. Less severe degrees of holoprosencephaly cause mental retardation ranging from profound to mild. The eyes may be closely set together, the nose may be malformed, and there may be cleft lip (premaxillary agenesis). Children who survive birth generally have facial deformities, spasticity, seizures, problems with regulating body temperature, apneic attacks (spells of stopped breathing), psychomotor retardation, sleep disorders, gastroesophageal reflux, and other problems. However, holoprosencephaly occurs along a continuum, and at the mild end of the spectrum development may be essentially normal.

Diagnosis Ultrasonic examination of the fetal brain has made early detection of holoprosencephaly common. In infants born live, a preliminary diagnosis may be based on extremely small head size (microcephaly) and on examination of the face, which is often deformed by the

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Autosomal dominant disorder A genetic disorder caused by a dominant mutant gene that can be inherited by either parent. Autosomal recessive disorder A genetic disorder that is inherited from parents that are both carriers, but do not have the disorder. Parents with an affected recessive gene have a 25% chance of passing on the disorder to their offspring with each pregnancy. Microcephaly An abnormally small head and underdeveloped brain. Prosencephalon The part of the brain that develops from the front portion of the neural tube. X-linked disorder Disorders caused by genes located on the X chromosome.

underlying developmental defects of the brain and skull. In particular, midfacial hypoplasia (subnormal growth of the features along the midline of the face) is strongly correlated with holoprosencephaly. Half of all cases of agnathia (total or virtual absence of a lower jaw) are also associated with holoprosencephaly. However, about 30% of cases of severe holoprosencephaly occur with normal development of the face. Ultrasound may give early warning of holoprosencephaly during fetal development; magnetic resonance imaging is the definitive method for diagnosing holoprosencephaly in non-severe cases.

Treatment team If holoprosencephaly is known to have occurred in the family, consultation with a geneticist before or during pregnancy may help a woman determine if she is at higher risk for conceiving infants with holoprosencephaly. If a woman has diabetes, she should see a doctor with expertise in diabetes care to obtain the best possible care before and during pregnancy, including help in achieving tight blood-glucose control, as this can reduce a diabetic woman’s risk of having a child with birth defects to near normal.

Prognosis The prognosis for an infant born with holoprosencephaly depends on the severity of the cerebral and other defects. The prognosis for an infant with severe holoprosencephaly is poor; most do not survive past six months, and those that do are likely to suffer profound mental retardation. At the mild end of the spectrum, where brain development may be nearly normal, a normal lifespan is likely. Resources BOOKS

Graham, David I., and Peter L. Lantos. Greenfield’s Neuropathology, 6th edition. Bath, UK: Arnold, 1997. OTHER

“Information about Holoprosencephaly.” Carter Centers for Brain Research in Holoprosencephaly and Related Malformations. (March 6, 2004). . “NINDS Holoprosencephaly Information Page.” National Institute of Neurological Disorders and Stroke. (March 6, 2004). . ORGANIZATIONS

Carter Centers for Research in Holoprosencephaly. c/o Texas Scottish Rite Hospital, P.O. Box 190567, 2222 Welborn Street, Dallas, TX 75219-9982. (214) 559-8411; Fax: (214) 559-7835. [email protected]. .

Larry Gilman, Ph.D.

❙ HTLV-1 associated

Treatment There is no cure for holoprosencephaly. Severe forms are fatal. For children with milder forms, treatment is directed at the symptoms rather than the disease. For example, drugs such as diazepam (Valium) and baclofen can be used to moderate spasticity (involuntary muscle tightening). Dorsal rhizotomy (cutting of the sensory spinal

myelopathy

Definition Damage to the nerves (myelopathy) of the spinal cord caused by infection with the human T lymphotrophic virus type-1 is termed HTLV-1 associated myelopathy.

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Key Terms

nerve roots), often done for the relief of intractable pain, can also be used to treat spasticity. Difficulty sleeping, common in children with holoprosencephaly, may be helped by such medications as Valium, chloral hydrate, or Melatonin. Low muscle tone in the esophageal sphincter, leading to gastroesophageal reflux (“spitting up” of the stomach contents into the esophagus and possibly out of the mouth, as occurs normally in small infants), can be treated with drugs that increase the speed with which the stomach and intestines pass material along and with antacids, which decrease the acidity of stomach contents and make gastroesophageal reflux less harmful. Emotional and intellectual care must be adjusted to the degree of retardation in each case.

HTLV-1 associated myelopathy

Description HTLV-1 associated myelopathy is evident mainly as a chronic weakening of muscles, especially those in the legs. Weakening can be so severe as to produce partial paralysis. The myelin covering of spinal cord nerve cells can become damaged, as can the elongated part of the cell termed the axon. HTLV-1 associated myelopathy is also known as tropical spastic paraparesis and additionally as HTLV1 associated myelopathy/tropical spastic paraparesis.

Key Terms Myelopathy A disorder in which the tissue of the spinal cord is diseased or damaged.

Diagnosis

Myelopathy occurs in approximately 0.25 % of those infected with HTLV-1, typically in adults aged 40–60. The viral infection is associated with diseases including adult Tcell leukaemia, Acquired Immunodeficiency Syndrome (AIDS), various neurological disorders, inflammation of the uveal tract of the eye, and degenerative or arthritic pain.

Diagnosis can be made using several clinical observations. A medical history will show that the current symptoms were not present during childhood. Within two years of the first appearance of symptoms, a person will likely have experienced an increase in the frequency of urination, and weakness, numbness, pains, or cramps in both legs. In a physical examination, an increased kneejerk reaction is seen. Difficulty using both legs is evident. Finally, eye abnormalities such as changes in the appearance of the pupil are present.

HTLV-1 is common in Japan, the Caribbean, and some areas of Africa. Correspondingly, the associated myelopathy is more prominent in these regions, compared to other areas of the globe.

The visualization of spinal cord nerve damage can also aid in diagnosis. Lesions and swelling associated with the spinal cord can be visualized by magnetic resonance imaging (MRI).

Demographics

Causes and symptoms HTLV-1 associated myelopathy is the result of infection with the HTLV-1 virus. The common routes of transmission are through breast milk, transfused blood (especially prior to 1989 when donated blood was not tested for HTLV-1), sexual intercourse, and drug injection. Until the viral link was established in the mid-1980s, HTLV-1 associated myelopathy was thought to result in the inflammation of the central nervous system caused by infection by the bacteria Treponema pallidum (the cause of syphilis) or Treponema pertenue (the cause of yaws), or by a nutritional deficiency. In addition to the damage to nerve myelin and axon, the white and grey matter of the spinal cord sometimes becomes infiltrated with certain white blood cells, along with nerve cell astrocytes. White lesions can develop along the length of the spinal cord. Occasionally, the entire cord can become swollen. Along with the progressively increasing muscle weakness, patients also can display impaired sense of touch and pain receptivity, and malfunction of muscles called sphincters, which can contract to restrict the flow of some body fluids and relax to resume flow. Leakage of urine is a problem in over 90% of those with this form of myelopathy. Patients can also develop eye inflammation, arthritis, dryness of the cornea and conjunctiva, and skin inflammation.

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Demonstration of the presence of HTLV-1 is an important part of the diagnosis. Antibodies to several viral proteins can be detected shortly after an infection begins. But, within a few months, an infection can become undetectable using antibody detection techniques. Thus, the absence of HTLV-1 antibodies does not necessarily rule out an infection. HTLV-1 genetic material can be detected from lymphocyte cells using a sensitive technique called polymerase chain reaction. A more reliable diagnostic finding can be an increased level of a compound called neopterin in the cerebrospinal fluid (CSF) that is obtained by a lumbar puncture. Neopterin is released by immune cells called macrophages when they are stimulated as part of an immune response to the infecting virus. As well, lymphocyte cells in the CSF can adopt a characteristic flower-like appearance.

Treatment team Family physicians, neurologists and other specialized clinicians, physical therapists, and caregivers are all part of the treatment team.

Treatment Currently, there is no specific treatment regimen for HTLV-1 associated myelopathy. Steroid medications help lessen symptoms and discomfort in many people. Drug therapy with lioresal or tizanidine can help relieve muscle spasms. The leakage of urine due to malfunction of the

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The use of plasmapheresis, in which plasma is withdrawn, antibodies removed, and the antibody-free liquid put back into the person, has not shown promise for HTLV-1 myelopathy. Interestingly, this technique is useful in treating myelin damage caused in other disorders such as Guillain-Barré syndrome.

National Organization for Rare Disorders. P.O. Box 1968, Danbury, CT 06813-1968. (203) 744-0100 or (800) 9996673; Fax: (203) 798-2291. [email protected]. .

Brian Douglas Hoyle, PhD

Huntington chorea see Huntington disease

Recovery and rehabilitation Physical and occupational therapy is useful in maintaining muscle function.

Clinical trials A clinical trial sponsored by the National Institute of Neurological Disorders and Stroke has been underway since 1997 in which blood samples are collected from patients in order to evaluate the functioning of the immune system and the levels of the virus during the course of the disease.

Prognosis While the disorder may become progressively worse, HTLV-1 associated myelopathy is seldom fatal. People with the disorder normally live for several more decades after being diagnosed. A better outcome typically results when steps are taken to lessen the chance of urinary tract infection (which can commonly occur when a catheter is used), and skin inflammation. Resources PERIODICALS

Zaninovic, V. “On the etiology of tropical spastic paraparesis and human T-cell lymphotropic virus-I-associated myelopathy.” Int J Infect Dis. 3, no. 3 (Spring 1999): 168–76. OTHER

National Institute of Neurological Disorders and Stroke. NINDS Tropical Spastic Paraparesis Information Page. (December 24, 2003). http://www.ninds.nih.gov/ health_and_medical/disorders/tropical_spastic_ paraparesis.htm>. ORGANIZATIONS

National Institute for Allergy and Infectious Diseases. National Institutes of Health, 31 Center Drive, Room 7A50, MSC 2520, Bethesda, MD 20892-2520. (301) 435-3848. . National Institute for Neurological Disorders and Stroke. P.O. Box 5801, Bethesda, MD 20824. (301) 496-5761 or (800) 352-9424. .

❙ Huntington disease Definition

First described by Dr. George Huntington in 1872, Huntington disease (HD) is a relatively common hereditary neurological condition that most commonly affects people in their adult years. HD is a progressive disorder that often involves thinking and learning problems, psychological disturbances, and abnormal movements. HD has been well studied and documented in family histories across the world. This ultimately led to the discovery of the HD gene, now known to be responsible for the disorder.

Description Huntington disease is also known by the name Huntington (or Huntington’s) chorea; “chorea” refers to neurological diseases that are characterized by spasmodic movements of the limbs and facial muscles. This is because about 90% of people with HD have chorea. These movements may be mild at first, but can worsen and become more involuntary with time. About two-thirds of people with HD first present with neurological signs, while others first have psychiatric changes. Other neurological signs include various abnormal movements, changes in eye movements, difficulty speaking, difficulty swallowing, and increased reflexes. A general decline in thinking skills occurs in essentially everyone with HD. This may begin as general forgetfulness and progress to difficulty gathering thoughts or keeping and using new knowledge. People with HD often also have psychiatric changes, including significant personality and behavior changes. The majority of those with HD first develops symptoms between the ages of 35 and 50 years. Symptoms vary considerably between people and sometimes within families, so it is difficult to predict an individual’s exact experience with HD if he or she is diagnosed with the condition. Disease progression occurs in everyone, with death usually seen 10–30 years after its onset.

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urinary sphincter muscle can be treated using oxybutynin, or managed by use of a catheter.

Huntington disease

Huntington Disease = Affected Symptomatic individual = Affected Presymptomatic individual

d.74y dx.68y

62y

60y d.58y dx.48y

d.30y dx.28y

54y

53y

d.59y dx.50y

40y

44y

d.48y dx.46y

46y

31y 28y

32y

d.50y dx.42y

d.30y dx.29y

27y

26y

See Symbol Guide for Pedigree Charts. (Gale Group.)

Demographics HD is estimated to occur in the United States and most of Europe at a rate of about five cases per 100,000 people. Pockets of populations exist where the prevalence may be a bit higher, such as those with western European ancestors. Conversely, HD is estimated to have a much lower prevalence in Japan, China, Finland, and Africa. For example, the frequency of HD in Japan has been estimated at between 0.1 and 0.38 per 100,000 people. Symptoms of HD typically begin after about age 35 years. However, in some families a juvenile form of HD has been seen with an onset of symptoms in the first or second decades of life. About a quarter of people with the condition are diagnosed past the age of 50 years. HD is a disease that affects males and females equally. Currently, genetic testing is widely available to identify a well-documented mutation in the HD gene. Testing is available for confirmation of a clinical diagnosis, or for those at risk but who, as yet, have no symptoms. Predictive genetic testing (for those who are asymptomatic) typically involves a specialized protocol with pretest and post-test counseling, requiring coordinated care with various medical professionals.

Causes and symptoms Some neurological changes have been seen in HD. However, the connection of many of these changes to the disease’s symptoms is still not understood. Atrophy of the

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basal ganglia and corpus striatum are common neurological findings in HD, which may worsen over time. Cortical atrophy is often present, and this may be seen with magnetic resonance imaging (MRI) or computed tomography (CT) scans. From pathology studies after death, brain atrophy is most prominent in the caudate, putamen, and cerebral cortex in people with HD. Total brain weight may be reduced by as much as 25–30% in people who have advanced cases of HD. A specific mutation in the HD gene called a triplet expansion causes symptoms of the condition to occur. The four different deoxyribonucleic acid (DNA) bases that make up genes are abbreviated as A, C, T, and G. Three DNA bases, CAG, are naturally repeated in the HD gene; a certain number of repeats is considered normal. People with symptoms of HD have a higher number of repeats than the usual range. Unfortunately, the number of CAG repeats can increase (or expand) from generation to generation, and this usually occurs in men. This genetic process is called anticipation; it cannot be predicted when and how the CAG repeats will expand in someone when they have children. A larger CAG repeat size is generally associated with developing symptoms at a younger age. HD is inherited in an autosomal dominant manner, which means that an affected individual has a one in two chance to pass the disease-causing mutation to his or her children, regardless of the gender. Children who inherit a disease-causing mutation will develop signs of HD at some point in their lives. On the other side of that, children

GALE ENCYCLOPEDIA OF NEUROLOGICAL DISORDERS

HD is usually first suspected with the observation or progression of abnormal movements. The initial reasons for seeking medical attention are often clumsiness, tremor, balance trouble, or jerkiness. Chorea is a frequent symptom. The areas of the body most commonly affected by chorea are the face, limbs, and trunk. As the chorea progresses, breathing, swallowing, and the mouth and nasal muscles may become involved. Muscles may become extremely rigid and gait may show signs of ataxia. Chorea may also be mixed with other movement disorders such as dystonia. Visual muscles may also be affected, and this can eventually lead to difficulties with vision, speech, swallowing, and breathing. Weight loss is a common symptom in HD, which may occur despite a proper intake of calories and nutrients. Because people with HD are frequently moving, it is thought this continual activity increases metabolic rates and may explain the weight loss. However, the exact cause for weight loss in HD is still not well understood. Mental impairment is an eventual sign of HD. This may begin at about the same time as movement abnormalities. If a diagnosis of HD is made, cognitive decline may have actually begun earlier, but might have gone unnoticed until other symptoms of the condition began to develop. General forgetfulness, loss of mental flexibility, difficulty with mental planning, and organization of sequential activities may be early signs of HD. Reduced attention and concentration spans are common, and this may lead to one being quite distractible. Aphasia and agnosia are less evident than in Alzheimer’s disease, but overall cognitive speed and efficiency are usually affected. The ability to speak is usually maintained, but people with HD may eventually have difficulty with complex words or finding the correct words to express their thoughts. Late-stage symptoms may include difficulty with visual and spatial relations. The last category of symptoms in HD is that involving psychological disturbances. Irritability and depression are common early signs of HD. People may initially be incorrectly diagnosed with psychiatric diseases like schizophrenia and delusional disorder, particularly if they have no other symptoms of HD. This is probably because a large percentage of people with HD have significant personality changes or affective psychosis. Behavioral issues can include intermittent explosiveness, apathy, aggression, alcohol abuse, sexual problems and deviations, paranoid delusions, and an increased appetite.

Suicide occurs in 5–12% of people with HD. Late-stage disease is often quite significant and can be disabling. Weight loss, sleep problems, and incontinence are common signs of advanced HD. Juvenile HD occurs when someone develops symptoms in the first two decades of life; this occurs in about 5–10% of all HD cases. Symptoms are distinct from those associated with adult-onset forms of HD. For example, chorea rarely occurs in people who develop HD in their first decade of life. However, dystonia and rigidity can be very significant for those individuals. Common characteristics of people with juvenile HD diagnosed before age 10 include declining performance in school, mouth muscle abnormalities, rigidity, and problems with their gait. Seizures are also a somewhat unique characteristic of juvenile HD. Complications related to immobility are often the cause of death in people with HD. Abnormal muscular movements, particularly those related to swallowing and breathing, may cause someone to die from aspiration pneumonia and other infections; such a cause of death occurs years after the onset of the disease. People with juvenile HD diagnosed between the age of 10 and 20 may have symptoms similar to adult-onset HD. Others may have more severe behavioral and psychiatric problems noticed before anything else. Common among people with juvenile HD is a father with adultonset HD.

Diagnosis Until the discovery of the HD gene on chromosome 4 in 1993, the diagnosis of the condition was made purely on a clinical basis. This can be somewhat challenging because of similarities with other hereditary and non-hereditary conditions involving chorea. A careful neurological examination and documentation of abnormal movements are important to diagnose HD. Sydenham’s chorea is a nonhereditary, infectious cause of chorea. It most often occurs in children and adolescents following a streptococcal infection, and the chorea associated is slightly different than that with HD. About 30% of people with rheumatic fever or polyarthritis develop Sydenham’s chorea two to three months later. Symptoms may even come back in pregnancy, or in people taking oral contraceptives. The chorea in Sydenham’s chorea is brisk and abrupt, but it is more flowing and somewhat slower in HD. Treatment for Sydenham’s chorea usually involves bed rest, sedation, and antibiotic therapy with medications like penicillin. Movements with characteristics of dystonia and athetosis, called choreoathetosis, are also common in HD.

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who do not inherit the mutation should not develop the disease. Strong family histories of HD have been well documented and studied across the globe.

Huntington disease

Key Terms Affective psychosis Abnormalities in mood, emotions, feelings, sensibility, or mental state.

Corpus striatum Region of the brain that contains the caudate nucleus and putamen.

Agnosia Inability to notice or process sensory stimuli.

Cortical Related to a cortex, such as the cerebral cortex.

Anticipation Genetic phenomenon in which a triple repeat DNA mutation expands in a future generation, causing symptoms to develop earlier. Aphasia Inability to communicate by speaking, writing, or signing. Aspiration pneumonia Infection of the lungs, caused by the presence of foreign material like food. Ataxia Uncoordinated muscular movement; often causes difficulty with walking and other voluntary movements.

Dementia General decline in cognitive function. Deoxyribonucleic acid (DNA) The chemical bases that make up genes. Dopamine Neurotransmitter chemical, typically found in the basal ganglia of the brain. Dystonia State of abnormal muscle tone, with either too much or too little. Gait

The way in which one walks.

Athetosis Slow, writhing involuntary movements that involve muscle flexing and extension.

Mutation A change in the order of DNA bases that make up genes, akin to a misspelling.

Atrophy Wasting or loss of tissue.

Neuropathy Term for any disorder affecting the nervous system or cranial nerves.

Basal ganglia Large masses of gray matter at the base of the brain; typically describes the corpus striatum and cell groups around it. Bradykinesia Slowness in movement. Caudate A region of gray matter near the lateral ventricle of the brain; also called caudate nucleus. Cerebral cortex Grey material covering the entire surface of the brain. Chorea Irregular, unpredictable, brief, jerky movements that randomly affect the body.

Polyarthritis Inflammation of several joints at the same time. Putamen Structure in the brain that is connected to the caudate nucleus and a component of the corpus striatum. Rheumatic fever Fever following a throat infection with group A Streptococcus, typically affecting children and young adults. Tremor An involuntary trembling movement.

People with HD may be able to more easily mask their movements at first, because they are not that intrusive in the early stages. Tardive dyskinesia is a nonhereditary cause of chorea that may be mistaken for HD in an individual on antipsychotic medications.

without symptoms may show signs of caudate atrophy before the disease even shows symptoms. These types of imaging studies can be useful to rule out other diagnoses that may mimic HD, because those may involve other specific brain changes.

Chorea occurs in 1–7% of people with lupus, and in a proportion of people with drug-related problems. It is important to rule out nonhereditary causes of chorea because treatments may exist for them, which may increase quality of life for the affected person.

An important step in diagnosing HD is to take a careful family history. Strong family histories with multiple generations affected, with roughly equal males and females affected, are common in HD.

Although very useful for many other neurological conditions, looking at the brain with techniques like magnetic resonance imaging (MRI) or computed tomography (CT) scans currently are not as helpful in diagnosing HD. These techniques may help find some typical brain changes in HD. For example, caudate atrophy is typically associated with advanced HD. Studies have shown that serial CT scans of the basal ganglia in at-risk individuals 424

Many hereditary conditions mimic HD. People who are diagnosed with HD much later in life may seem similar to people with Parkinson’s disease, because abnormal movements may be the primary symptom. Neuroacanthocytosis is a hereditary condition with chorea, but it should be considered if muscle loss, absent lower limb tendon reflexes, neuropathy, and specific results on a blood test are present. Benign hereditary chorea is an autosomal dominant condition in which the chorea is not progressive, and

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Often, diagnosis is most clearly made with genetic testing, which is done to confirm a suspected clinical diagnosis. Genetic testing identifies the exact number of CAG repeats in each copy of a person’s HD gene. There are several CAG repeat ranges that may be found through testing. Each genetic laboratory may use slightly different ranges, so test results should be interpreted carefully. Generally, a range of 10–27 CAG repeats is considered to be normal. If someone has results in these ranges, this person does not have HD, and will not develop signs of it. A range of 27–35 CAG repeats will not cause symptoms of HD in the person. In this range, the repeat size may rarely increase when passed on to children. In other words, the person with this test result will not develop symptoms of HD, but he or she may have a child who develops symptoms. This would particularly be the case if the person were a man, because of the anticipation phenomenon. A range of 36–39 CAG repeats is considered a range where the person may or may not develop HD symptoms at some point in his or her life. Additionally, the repeat may or may not expand to his or her children. People with an HD gene that has greater than 39 CAG repeats will develop symptoms of HD at some point in their lives. They would have a 50% chance of passing this gene on to future children. People with juvenile HD usually have much larger CAG repeat sizes than those who have the typical form of HD. Despite this, it is still impossible to predict exactly when someone may develop symptoms, or to predict the exact symptoms they will experience. Genetic testing for those who have symptoms is fairly straightforward, and often ordered with the aid of a neurologist. Predictive testing for HD, as it is called when the person does not have symptoms, is a bit more complicated. This is because there are many complex factors in the testing process. Ideally, at-risk asymptomatic individuals have several appointments before genetic testing is performed. They should see a neurologist for a thorough examination to identify any subtle signs of HD. They should also see a neuropsychologist for an evaluation. The neuropsychologist can help assess whether a person is a good candidate for genetic testing, potentially reducing the risk for poor

outcomes, like suicide, following positive results. Individuals should also see a medical geneticist and genetic counselor to receive thorough information about the risks, benefits, and limitations of genetic testing. Much has been studied about the myriad of issues with genetic testing in HD. Risks from any outcome can be considerable, and these may include a sudden change in family dynamics, self-image, or serious emotional and psychological harms. Health, life, or disability insurance discrimination from HD testing may be a possibility, especially related to positive results. Employment may also be an issue. In October 2003, a young teacher in Germany was refused a permanent job because members of her family have HD; she was found to be at risk for the condition during a required governmental medical examination. Currently, there is not enough documentation in the medical literature to know what the actual risks are related to these issues. Awareness and discussion of these issues are important in pretest counseling. Limitations and benefits from genetic testing should be given equal weight as well. Results may not be easily understood, simply identifying one and one’s children to be potentially at risk. These types of vague results can cause great angst to an at-risk individual. However, benefits from testing may include relief from years of worry, empowerment from medical knowledge, and the ability to make life plans or tailor medical care based upon more accurate information. Generally, at-risk asymptomatic children under age 18 are not tested for HD. The decision to learn their genetic status should be theirs, and at a time they feel is appropriate. Along the same lines, prenatal genetic testing for HD is not done, except in cases involving special circumstances or assistive reproductive techniques.

Treatment team Treatment for people with HD is highly dependent on their symptoms. A multidisciplinary team and approach can be very helpful. A treatment team may include a neurologist, neuropsychologist, medical geneticist, genetic counselor, physical therapist, occupational therapist, speech therapist, registered dietitian, social worker, psychotherapist, psychiatrist, ophthalmologist, and a primary care provider. Some hospitals offer day clinics devoted to people with HD, which makes things much easier in terms of coordinating appointments. Pediatric specialists in these fields may help in the care for children.

Treatment Currently, there is no known cure for Huntington disease. No specific treatment is known to slow, stop, or reverse the progressive nature of the disease. Current

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does not involve any cognitive decline. Dentatorubropallidoluysian atrophy (DRPLA) is another hereditary condition that mimics HD; it typically affects adults and involves dementia, ataxia, and seizures, along with chorea. As a group, the hereditary spinocerebellar ataxias (SCAs) may mimic some of the movement abnormalities seen in HD. However, the psychological and cognitive components may not be present in the SCAs.

Huntington disease

treatment for HD is mainly focused on relieving symptoms and reducing the impact of physical and mental complications related to the disease. Medications are available to help treat chorea in HD, including therapies for blocking dopamine receptors, or those that deplete dopamine from its natural storage sites in the brain. Medications like these are tetrabenazine, pimozide, and haloperidol. They can have side effects, like drowsiness and a lessened ability to make voluntary movements. Some find the side effects to be more troublesome than the chorea, so medications should be prescribed under careful supervision. Psychiatric problems in HD are often treated with medications as well. Some selective serotonin reuptake inhibitors (SSRIs) with trade names like Celexa, Paxil, Prozac, and others have been effective. Some tricyclic antidepressants like Nordil, Marplan, and Eldepryl have been effective. Lastly, some monoamine oxidase inhibitors (MAOIs) like Elavil, Tofranil, and Anafranil have been useful in treating depression. Benzodiazepine and antipsychotic drugs can be used to treat anxiety, irritability, and agitation in HD. It is rare to find a medication without side effects, and drug interactions are also important to consider. As yet, no medications have been found helpful to treat the cognitive problems in HD. Other therapies have been tested through clinical trials to see whether the disease progression may be slowed in any way. A combination of coenzyme Q10 and remacemide has been tested in mice, showing it to be helpful in reducing weight loss and brain loss. In a study by The Huntington Study Group in 2001, people with earlystage HD were given coenzyme Q10 or remacemide, but neither had significant effects. A 2000 study found that minocycline, an antibiotic, delayed motor decline in mice by 14%. Riluzole is a drug currently used to treat people with amyotrophic lateral sclerosis (ALS, or Lou Gehrig’s disease). In clinical trials with HD patients in 1999, the drug reduced chorea in about a third of people over six weeks. Behavior was improved by about 61% after 12 months. Studies are under way to see whether transplanting fetal cells from the corpus striatum will be helpful to treat people with HD. This follows closely on the heels of similar trials with people who have Parkinson’s disease. As of early 2004, preliminary results seem promising but much more time is needed to fully study and interpret them.

Recovery and rehabilitation Supportive therapy for people with HD is very helpful, and often greatly needed as time goes on. It may begin shortly after diagnosis and continue for years, until the disease becomes advanced and supportive care is needed. 426

Physical therapy, speech therapy, and dietary advice can be extremely important and most effective when in tandem. Special consideration should be given to nursing and supportive care, home health care options, diet, special adaptive equipment, and eligibility for governmental benefits. A practical approach with common sense, emotional support, and careful attention to a family’s needs is effective for many people with HD.

Clinical trials As of early 2004, many clinical trials were under way to study Huntington disease: • Family Health after Predictive Huntington Disease (HD) Testing, sponsored by National Institute of Nursing Research (NINR). • Minocycline in Patients with Huntington’s Disease, sponsored by FDA Office of Orphan Products Development. • Prospective Huntington At-Risk Observational Study (PHAROS), sponsored by National Institute of Neurological Disorders and Stroke (NINDS) and National Human Genome Research Institute (NHGRI). • Neurobiological Predictors of Huntington’s Disease (PREDICT-HD), sponsored by NINDS. • Brain Tissue Collection for Neuropathological Studies, sponsored by National Institute of Mental Health (NIMH).

Prognosis Prognosis has historically been somewhat bleak for people with HD. Complications related to movement abnormalities and immobility, such as pneumonia and respiratory complications, are a common cause of death in HD. Though no cure is currently available, treatments or therapies may be available in the future to maintain a better quality of life, and these continue to offer hope. Resources BOOKS

Parker, James N., and Philip M. Parker. The Official Patient’s Sourcebook on Huntington’s Disease: A Revised and Updated Directory for the Internet Age. San Diego: Icon Health Publishers, 2002. Quarrell, Oliver. Huntington’s Disease: The Facts. Oxford: Oxford University Press, 1999. PERIODICALS

Burgermeister, Jane. “Teacher Was Refused Job because Relatives Have Huntington’s Disease.” British Medical Journal (October 11, 2003) 327 (7419): 827. Grimbergen, Yvette A. M., and Raymond A. C. Roos. “Therapeutic Options for Huntington’s Disease.” Current Opinion in Investigational Drugs (2003) 4(1): 51–54.

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WEBSITES

Caring for People with Huntington’s Disease. (June 2, 2004). . GeneTests/GeneReviews. (June 2, 2004). . National Institute of Neurological Disorders and Stroke. (June 2, 2004). . Testing for Huntington Disease: Making an Informed Choice. (June 2, 2004). . Testing Guidelines in Huntington’s Disease. (June 2, 2004). . ORGANIZATIONS

Huntington’s Disease Society of America. 158 West 29th Street, 7th Floor, New York, NY 10001-5300. (212) 2421968 or (800) 345-HDSA (4372); Fax: (212) 239-3430. [email protected]. . Huntington Society of Canada. 151 Frederick Street, Suite 400, Kitchener, Ontario N2H 2M2, Canada. (519) 7497063 or (800) 998-7398; Fax: (519) 749-8965. info@ hsc-ca.org. . International Huntington Association. Callunahof 8, 7217 St Harfsen, The Netherlands. + 31-573-431595. iha@ huntington-assoc.com. .

Deepti Babu, MS, CGC

❙ Hydantoins Definition

Hydantoin anticonvulsants are most commonly used in the treatment of seizures associated with epilepsy, a neurological dysfunction in which excessive surges of electrical energy are emitted in the brain. Some hydantoins, such as phenytoin, are also indicated for use as skeletal muscle relaxants and in the treatment of severe nerve pain, as in trigeminal neuralgia.

Purpose While hydantoins control the seizures associated with epilepsy, there is no known cure for the disorder. The precise mechanisms by which hydantoins work are unknown, but they are thought to exert their therapeutic effect by depressing abnormal neuronal discharges in the central nervous system (CNS).

Description For the treatment of seizures, hydantoins may be used alone or in combination with other anti-epileptic drugs (AEDs) or anticonvulsants. However, the use of multiple anticonvulsants and AEDs should be carefully monitored by the prescribing physician. Phenytoin, mephenytoin, ethotoin, and fosphenytoin are the individual hydantoin anticonvulsants. They are marketed under several brand names, including Cerebyx, Dilantin, Mesantoin, Peganone, and Phentek.

Recommended dosage Hydantoins anticonvulsants are available in oral and injectable (phenytoin and fosphenytoin only) forms. Orally-administered hydantoins are available in the form of tablets, capsules, or oral suspension. Hydantoins are prescribed by physicians in varying daily dosages. Some hydantoin anticonvulsants are taken in divided daily doses, twice daily. Others are administered in a single daily dose. A double dose of any hydantoin should not be taken. If a dose is missed, it should be taken as soon as possible. However, if it is almost time for the next dose, the missed dose should be skipped. It may take several weeks to realize the full benefits of hydantoins. Beginning any course of treatment including hydantoins requires a gradual dose-increasing regimen. Children and adults typically take a smaller daily dose for the first two weeks. Daily dosages of hydantoins may then be slowly increased over time. When ending a course of treatment that includes hydantoin anticonvulsants, physicians typically taper the patient’s daily dose over a period of several weeks. Suddenly stopping treatment with hydantoins may cause seizures or pain to occur or return with greater frequency.

Precautions Persons taking hydantoins should consult the prescribing physician before taking non-perscription medications. Patients should avoid alcohol and CNS depressants (medications that make one drowsy such as antihistimines, sleep medications, and some pain medications) while taking hydantoins. These medications may increase the frequency and severity of the side effects of hydantoins. Hydantoins may also potentiate the action of alcohol, and alcohol can increase the risk or frequency of seizures. Hydantoins may not be suitable for persons with a history of thyroid, liver, or kidney disease, depressed renal function, diabetes mellitus, porphyria, lupus, mental illness, high blood presure, angina (chest pain), or irregular heartbeats and other heart problems. Before beginning treatment with hydantoins, patients should notify their

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Margolis, Russell L., and Christopher A. Ross. “Diagnosis of Huntington Disease.” Clinical Chemistry (2003) 49(10): 1726–1732. Sutton Brown, M., and O. Suchowersky. “Clinical and Research Advances in Huntington’s Disease.” The Canadian Journal of Neurological Sciences (2003) 30 (Suppl. 1): S45–S52.

Hydantoins

the following symptoms should contact their physician immediately:

Key Terms Epilepsy A disorder associated with disturbed electrical discharges in the central nervous system that cause seizures. Neurogenic pain Pain originating in the nerves or nervous tissue. Trigeminal neuralgia A disorder affecting the trigeminal nerve (the 5th cranial nerve), causing episodes of sudden, severe pain on one side of the face.

• rash, excessive bruising, or bluish patches on the skin • bleeding in the gums or mouth • ringing or vibrations in the ears • general loss of motor skills • severe lack of appetite • altered vision • difficulty breathing • chest pain or irregular heartbeat • faintness or loss of consciousness

physician if they consume a large amount of alcohol, have a history of drug use, are nursing, pregnant, or plan to become pregnant. Physicians usually advise women of child-bearing age to use effective birth control while taking hydantoin anticonvulsants. Many anticonvulsant medications, including hydantoins, have been shown to increase the risk of birth defects. Patients who become pregnant while taking hydantoins should contact their physician. Some hydantoin anticonvulsant medications may be prescribed for children; however, children sometimes experience increased side effects. Research indicates that some children who take high doses of hydantoins for an extended period of time may experience mild learning difficulties or not perform as well in school.

Side effects In some patients, hydantoins may produce some mild side effects. Drowsiness and dizziness are the most frequently reported side effects of anticonvulsants. Other general side effects of hydantoins that usually resolve without medical attention include: • mild coordination problems

• persistent fever or pain

Interactions Hydantoins may have negative interactions with some antacids, anticoagulants, antihistimines, antidepressants, antibiotics, pain killers and monoamine oxidase inhibitors (MAOIs). Other medications such as amiodarone, diazoxide, felbamate, phenybutazone, sulfonamides (sulfa drugs), corticosteroids, sucralfate, rifampin, and warfarin may also adversely react with hydantoins. Some hydantoins should not be used with other anticonvulsants. For example, phenytoin (a hydantoin) when used with valproic acid (a non-hydantoin anticonvulsant) may increase the seizure frequency. However, some patients may use hydantoins with other seizure prevention medications if carefully monitored by a physician. Hydantoins may decrease the effectiveness of contraceptives, including oral contraceptives (birth control pills), progesterone implants (Norplant), and progesterone injections (Depo-Provera). Resources BOOKS

• constipation

Weaver, Donald F. Epilepsy and Seizures: Everything You Need to Know. Firefly Books, 2001.

• muscle twitching

PERIODICALS

• unpleasant taste in mouth or dry mouth

“Risk of birth defects with anticonvulsants evaluated.” Psychopharmacology Update 12, no. 5 (May 2001): 3.

• unusual or excessive hair growth on face or body. Many of these side effects disappear or occur less frequently during treatment as the body adjusts to the medication. However, if any symptoms persist or become too uncomfortable, the perscribing physician should be consulted. Other, uncommon side effects of hydantoins may indicate an allergic reaction or other potentially serious condition. A patient taking hydantoin who experiencs any of 428

OTHER

“Anticonvulsants, Hydantoin (Systemic).” Medline Plus. National Library of Medicine. (April 20, 2004). . ORGANIZATIONS

Epilepsy Foundation. 4351 Garden City Drive, Landover, MD 20785-7223. (800) 332-1000. .

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Adrienne Wilmoth Lerner

carbon monoxide early in pregnancy has also been implicated as a possible cause, along with the possibility of early stroke in the developing fetus, or as a result of infection with some viruses.

Diagnosis

❙ Hydranencephaly Definition

Hydranencephaly is a rare congenital deformity (a deformity that occurs during fetal development) that is characterized by the absence of the cerebral hemispheres of the brain. Instead, the regions of the brain known as the left and right cerebral hemispheres are replaced by sacs that are filled with cerebrospinal fluid.

Description The absence of the cerebral hemispheres may not be apparent in the first days following birth. The normal and involuntary actions of a newborn such as sucking, swallowing, and crying all occur, as the brainstem controls these actions, and it is usually normal. Moreover, the baby with hydranencephaly appears physically normal, including the size of the head. The normal behaviors of a growing infant reflect the functions of the left and right cerebral hemispheres. The left hemisphere is normally associated with the acquisition of language. The right hemisphere participates in the perception of space and distance. These sorts of skills are not yet developed in a newborn. Within several weeks to months of birth, the symptoms of hydranencephaly can become apparent.

Demographics Hydranencephaly is a rare occurrence. It is estimated that one or two babies are born with hydranencephaly worldwide for every 10,000 births. There is no indication that any gender or race is any more susceptible to the disorder.

Causes and symptoms Within a few weeks of birth, the infant typically becomes irritable and the contraction of the muscles (muscle tone) becomes more pronounced. Muscles may spasm. Seizures can occur. Other symptoms that can develop with time include poor vision or the total loss of vision, poor or no growth, deafness, paralysis, and impaired intellectual development (such as language difficulty). Hydranencephaly may be caused by a genetic defect, infection associated with vessels, or a trauma that occurs after the twelfth week of pregnancy. Maternal exposure to

Diagnosis is based on the appearance of symptoms noted above. Diagnosis may not be made for weeks or months following birth, because of the initial normal appearance and behavior of the newborn. Prior to birth, ultrasound can reveal hydranencephaly, although techniques for surgical correction in the fetus have not been developed.

Treatment team A range of medical help, from a family practitioner to pediatric surgeon, can be involved. As well, nurses and family members are part of the care-giving team. Social service workers can refer parents of children with hydranencephaly to community support organizations.

Treatment There is no definitive treatment for hydranencephaly. Usually, symptoms are treated as they occur and support is provided to make the child as comfortable and happy as possible. Medications are given to control seizures and if excess cerebrospinal fluid collects near the brainstem, a shunt is usually surgically inserted to facilitate redirection of the excess fluid.

Recovery and rehabilitation Rehabilitation is not stressed for the infant with hydranencephaly, as the long-term prognosis is poor. Physical and occupational therapists may assist in providing treatment to maintain muscle tone for as long as possible, and positioning aids when necessary. Medications are given to control seizures and for comfort.

Clinical trials As of January, 2004, there were no clinical trials underway or planned in the United States for the study of hydranencephaly. Organizations such as the National Institute for Neurological Disorders and Stroke undertake and fund studies designed to reveal more about the normal development patterns of the brain. By understanding how development can be disrupted, scientists attempt to learn strategies for detecting defects and methods to correct them.

Prognosis The long-term outlook for children with hydranencephaly is poor. Most children die in their first year of life, although survival past the age of 10 can rarely occur.

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American Epilepsy Society. 342 North Main Street, West Hartford, CT 06117-2507. .

Hydrocephalus

Key Terms Brainstem The stalk of the brain that connects the two cerebral hemispheres with the spinal cord. It is involved in controlling vital functions, movement, sensation, and nerves supplying the head and neck.

National Organization for Rare Disorders. 55 Kenosia Avenue, Danbury, CT 06813-1968. (203) 744-0100 or (800) 9996673; Fax: (203) 798-2291. [email protected]. .

Brian Douglas Hoyle, PhD

Seizure A sudden attack, spasm, or convulsion.

❙ Hydrocephalus Currently, the oldest known survivor was 20 years, 6 months old.

Special concerns Providing support for parents of babies born with hydranencephaly includes genetic counseling and referrals to support groups, where parents can learn practical advice and share information with other parents of children similarly affected. Additionally, mothers who have given birth to a baby with hydranencephaly may be tested for some of the viruses suspected in playing a part in the fetal development of hydranencephaly, including toxoplasmosis, cytomegalovirus, and Herpes simplex virus. Resources PERIODICALS

Covington, C., H. Taylor, C. Gill, B. Padaliya, W. Newman, J. R. Smart III, and P. D. Charles. “Prolonged survival in hydranencephaly: a case report.” Tennessee Medicine (September 2003): 423–424. Lam, Y. H., and M. H. Tang. “Serial sonographic features of a fetus with hydranencephaly from 11 weeks to term.” Ultrasound Obstetrics and Gynecology (July 2000): 77–79. OTHER

“NINDS Hydranencephaly Information Page.” National Institute for Neurological Diseases and Stroke. (January 20, 2004). . ORGANIZATIONS

March of Dimes Birth Defects Foundation. 1275 Mamaroneck Avenue, White Plains, NY 10605. (914) 428-7100 or (888) 663-4637; Fax: (914) 428-8203. askus@ marchofdimes.com. . National Information Center for Children and Youth with Disabilities. P.O. Box 1492, Washington, DC 20013-1492. (202) 884-8200 or (800) 695-0285; Fax: (202) 884-8441. [email protected]. . National Institute for Neurological Diseases and Stroke (NINDS). 6001 Executive Boulevard, Bethesda, MD 20892. (301) 496-5751 or (800) 352-9424. . 430

Definition

The word hydrocephalus derives from the Greek words hydro, meaning water, and cephalus, meaning head. Hydrocephalus is the result of the excessive accumulation of fluid in the brain. Traditionally, hydrocephalus has been described as a disease characterized by increased intracranial pressure (ICP), increased cerebrospinal fluid (CSF) volume, and dilatation of the CSF spaces known as cerebral ventricles.

Description Hydrocephalus is the result of an imbalance between the formation and drainage of cerebrospinal fluid. This imbalance appears when an injury or illness alters the circulation of CSF; one or more of the ventricles of the brain become enlarged as CSF accumulates. However, hydrocephalus is not a single disease entity, as a wide number of underlying diseases are responsible for causing retention of CSF, resulting in ventricular dilatation and increased intracranial pressure (ICP). In infants and children, for example, hydrocephalus usually results from a birth defect, viral infection, head injury, hemorrhage, meningitis, or tumor. In adults, the causes of hydrocephalus include brain damage due to stroke or injury, Alzheimer’s disease, or obstruction of the ventricles. Often, the cause is unknown. Conditions responsible for hydrocephalus in a fetus include infantile congenital (present at birth) hydrocephalus, hydrocephalus associated with encephalocele or myelomeningocele, posthemorrhagic hydrocephalus in newborns, and postmeningitic hydrocephalus. Conditions responsible for hydrocephalus in adults include hydrocephalus following subarachnoid hemorrhage, idiopathic adult hydrocephalus, and posttraumatic hydrocephalus. Tumors can also result in hydrocephalus in both children and adults. Based on the different kind of CSF circulation in the brain, hydrocephalus can be divided into two types: communicating and non-communicating. In communicating hydrocephalus, the CSF circulation pathways are competent from the ventricles inside of the brain to the fluid spaces just below the third ventricle. Non-communicating (obstructive) hydrocephalus refers to hydrocephalus that

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Hydrocephalus

Sideview of the skull of infant suffering from hydrocephalus. (© Lester V. Bergman/Corbis. Reproduced by permission.)

develops from a blockage of the normal circulation of CSF within the brain. In most cases, it refers to a blockage between the third and fourth ventricles.

Demographics Overall incidence of infantile hydrocephalus is approximately one to two per 1,000 live births. The overall prevalence of hydrocephalus in the United States is about 0.5%. When cases of spina bifida are included, congenital hydrocephalus occurs in two to five births per 1,000 births. The incidence of acquired hydrocephalus in adults is not known because it occurs as a result of injury, illness, or environmental factors. Normal pressure hydrocephalus was found to be significantly more prevalent in males, and can occur in adults of any age group. The age distribution in children and teenagers is disputed.

Causes and symptoms Approximately 16 oz (500 ml) of CSF are formed within the brain each day, by cells located on the wall of the four ventricles in the brain. Once formed, CSF circulates among all the ventricles before it is absorbed. The normal adult volume of circulating CSF is about 2 oz

(150 ml). The CSF turnover rate is more than three times per day. Because production is independent of absorption, reduced absorption causes CSF to accumulate within the ventricles. Hydrocephalus can be subdivided into three forms, involving the following: • Disorders of cerebrospinal fluid circulation. Tumors, hemorrhages, congenital malformations, and infections can cause such obstructions in the circulation of cerebrospinal fluid. • Disorders of cerebrospinal fluid absorption, resulting from diseases such as the superior vena cava syndrome and sinus thrombosis. • Disorders of cerebrospinal fluid production: This is the less common form of hydrocephalus resulting from tumors that secrete cerebrospinal fluid in excess of its absorption. Congenital hydrocephalus is thought to be caused by a complex interaction of genetic and environmental factors. The origin of hydrocephalus in congenital cases is unknown. Very few cases (less than 2%) are inherited (X-linked hydrocephalus). The most common causes of

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hydrocephalus in acquired cases are tumor obstruction, trauma, intracranial hemorrhage, and infection. The two most common adult forms of hydrocephalus are hydrocephalus ex-vacuo and normal pressure hydrocephalus. Hydrocephalus ex-vacuo occurs when a stroke or injury damages the brain, yielding a brain substance. Although there is more CSF than usual, the CSF pressure may or may not be elevated. Normal pressure hydrocephalus is an abnormal increase of CSF in the brain’s ventricles due to the gradual blockage of the CSF-draining pathways. This may result from a subarachnoid hemorrhage, head trauma, infection, tumor, or complications of surgery. The ventricles enlarge to handle the increased volume of the CSF, and the compression of the brain from within by the fluid-filled ventricles destroys or damages brain tissue. Fluctuation of CSF pressure from high to normal to low can also be present. For congenital-onset hydrocephalus, early symptoms include enlargement of the head (increased head circumference), bulging fontanelles (soft spots) with or without enlargement of the head size, separation of sutures (the flexible and fibrous joints between the skull bones of an infant), and vomiting. Symptoms of continued hydrocephalus include irritability and muscle spasticity. Late symptoms of congenital-onset hydrocephalus seen in children up to five years of age include decreased mental function, delayed development, slow or restricted movement, difficulty feeding, lethargy, and delayed growth. In children, symptoms depend on the amount of damage caused by ICP. Symptoms may be similar to many of those in infants or may include headache, vomiting, vision changes such as crossed eyes, uncontrolled eye movements, loss of coordination, poor gait (walking pattern), mental confusion, or psychosis. For adult-onset hydrocephalus, headaches and nausea are the most common symptoms. Other signs of the condition include difficulty focusing the eyes, unsteady gait, weakness of the legs, sudden falls, and a distinctive inability to walk forward. As hydrocephalus progresses, decreased mental activity appears, including lethargy, apathy, impaired memory, and speech problems. Urinary and bowel incontinence can also occur. During the final stage, dementia involving loss of movement, sensory functions, and cognitive abilities may result.

Diagnosis Ultrasound can be used to diagnose prenatal hydrocephalus. Although fetal hydrocephalus may be an isolated finding, it is more frequently found along with other cerebral anomalies, including neural tube defects. Diagnosis after birth may be suggested by symptoms; however, imaging studies of the brain are the mainstay of diagnosis. Computed tomography (CT) and magnetic resonance 432

imaging (MRI) reveal enlarged ventricles and may indicate a specific cause of hydrocephalus, such as a tumor or hemorrhage. The presence of papilledema (elevation or swelling of the optic disc) also indicates that hydrocephalus that is well developed. In rare cases, long-standing hydrocephalus causes blindness. Small abnormalities that may not be seen with CT scanning, such as cysts and abscesses, are often seen with MRI. These studies can also help the neurosurgeon differentiate between communicating and non-communicating hydrocephalus. In cases of suspected normal pressure hydrocephalus, a lumbar puncture (spinal tap) may help determine CSF pressure. Also, a cisternagram can be useful to evaluate the dynamics of CSF flow in the brain and spinal chord. Cisternography can reveal CSF concentration, obstruction, leakage, and pressure. Also, certain biochemical markers in the blood have been described in the disease. They include increased neurofilament light protein (NFL) and tau protein, both markers of neuronal degeneration; increased myeline basic protein (a marker of demyelination; and albumin); and a marker of the bloodbrain barrier function.

Treatment team Treatment of hydrocephalus for children or adults will likely involve a neurologist, neurosurgeon, obstetrician, pediatrician, and specialty nurses and physical therapists.

Treatment Medical treatment is first aimed at reducing intracranial pressure, while the need for a more permanent solution is determined. Reduction of fluid intake and administration of drugs such as mannitol, glycerol, urea (drugs with an osmotic effect), or furosemide (a diuretic) are able to reduce ICP and CSF production. External drainage of the CSF is useful for urgent reduction of intracranial pressure, as well as of ventricular or subarachnoid hemorrhage. Complications include overdrainage, blocked tube, or bacterial contamination. The placement of a permanent ventricular shunt (internal shunting) is a common procedure. Around 33,000 shunts are placed in the United States each year; almost half of them to replace previous shunt devices. CSF from the ventricles in the brain is usually shunted to the peritoneum, pleura, ureter, bladder, or vascular spaces such as the jugular or subclavian veins. Most shunts are connected to the peritoneum. Some shunts operate according to intracranial pressure by using a valve system able to regulate the flow at a pressure close to the normal values of ICP. Others are programmable and can be adjusted to open at a given ICP. Complications include overdrainage that may cause intracranial hypotension, subdural hematoma,

GALE ENCYCLOPEDIA OF NEUROLOGICAL DISORDERS

Cerebrospinal fluid (CSF) The clear fluid made in the ventricular cavities of the brain that bathes the brain and spinal cord. Gait Posture and manner of walking. Hydrocephalus A condition characterized by the abnormal accumulation of cerebrospinal fluid within the ventricles of the brain. Increased intracranial pressure (ICP) Increased pressure within the skull caused by extra tissue or fluid in the brain. Papilledema Swelling of the optic disc, where the optic nerve enters the eyeball, or elevation of the optic nerve, and indication of increased intracranial pressure. Ventricle The cavities or chambers within the brain that contain the cerebrospinal fluid.

shunt occlusion, and infection. The risk of shunt failure is greater within the first year (between 25–40% of shunts must be replaced). The subsequent failure rate is around 5% for each year. Other surgical procedures include, in some cases, choroid plexectomy, third ventriculostomy, and ventricular reservoir. Ventricular reservoir is basically a catheter inserted into a ventricle of the brain to draw CSF. This procedure is much simpler than placing a full shunt system and is used to provide temporary control of ICP until a full shunt can be placed.

Recovery and rehabilitation Hydrocephalus is a chronic condition, and clinical symptoms are based on the time of insurgence of the disease. With appropriate, early treatment, a normal lifespan with few limitations can be reached. After surgery, specially trained medical professionals carefully monitor the patient. Some symptoms such as headaches may disappear immediately due to the release of excess pressure. The symptoms associated with normal pressure hydrocephalus (walking difficulties, mild dementia, poor bladder control) may improve quickly, or may take weeks to months to improve. In some patients, little or no improvement is also possible. The length of the patient’s hospital stay will be determined by the rate of recovery. If neurological problems persist, rehabilitation may be required to further the patient’s improvement. However, recovery may be limited by

Clinical trials Ventricular shunts are the most common surgical treatment for hydrocephalus and appear to be the safest. It is possible that choroid plexectomy and third ventriculostomy may become more feasible in the future if better procedures and equipment are developed. As of mid-2004, several clinical trials to study hydrocephalus were underway, including a trial to evaluate the efficacy and safety of endoscopic choroid plexus coagulation with third ventriculostomy in the treatment of idiopathic normal pressure hydrocephalus, sponsored by the Frenchay Hydrocephalus Research Fund. The National Institute of Neurological Disorders and Stroke is sponsoring a study to establish the physiology of syringomyelia. Updated information on these and other ongoing clinical trials may be found at the National Institutes of Health website for clinical trials at .

Prognosis Untreated hydrocephalus has a survival rate of 40–50%, with the survivors having varying degrees of intellectual, physical, and neurological disabilities. Prognosis for treated hydrocephalus varies, depending on the cause. If the child survives for one year, more than 80% will have a fairly normal lifespan. Approximately onethird will have normal intellectual function, but neurological difficulties may persist. Hydrocephalus not associated with infection has the best prognosis, and hydrocephalus caused by tumors has a very poor prognosis. About 50% of all children who receive appropriate treatment and follow up will develop IQs in the near-normal or normal range. Resources BOOKS

Matsumoto, Satoshi. Hydrocephalus: Pathogenesis and Treatment. New York: Springer-Verlag, 1991. The Official Parent’s Sourcebook on Hydrocephalus: A Revised and Updated Directory for the Internet Age. San Diego: Icon Group International, 2002. Toporek, Chuck, and Kellie Robinson. Hydrocephalus: A Guide for Patients, Families and Friends. Sebastopol, CA: Patient-Centered Guides, 1999. PERIODICALS

Arriada, N., and J. Sotelo. “Review: Treatment of Hydrocephalus in Adults.” Surg Neurol. (2002) Dec 58 (6): 377–84.

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Key Terms

the extent of the damage already caused by the hydrocephalus. Because hydrocephalus is an ongoing condition, patients do require long-term follow up. Follow-up diagnostic tests, including CT scans, MRI, and x rays, may be performed to determine if the shunt is working correctly.

Hydromyelia

Davis, G. H. “Fetal Hydrocephalus.” Clin Perinatol. (2003) Sep 30 (3): 531–9. Meier, U., and C. Miethke. “Predictors of Outcome in Patients with Normal-Pressure Hydrocephalus.” J Clin Neurosci. (2003) Jul 10 (4): 453–9. OTHER

“NINDS Hydrocephalus Information Page.” National Institute of Neurological Disorders and Stroke. May 15, 2004 (May 22, 2004). . “What is Hydrocephalus?” Hydrocephalus Foundation, Inc. May 15, 2004 (May 22, 2004). . ORGANIZATIONS

Hydrocephalus Association. 870 Market Street, Suite 705, San Francisco, CA 94102. (415) 732-7040 or (888) 598-3789; Fax: (415) 732-7044. [email protected]. . National Hydrocephalus Foundation. 12413 Centralia Road, Lakewood, CA 90715-1623. (562) 402-3523 or (888) 857-3434; Fax: (562) 924-6666. [email protected]. .

Antonio Farina, MD, PhD

❙ Hydromyelia Definition

Hydromyelia (HM) is a condition characterized by widening of the central canal of the spinal cord. Fluid can accumulate in this space, creating increased pressure on the spinal cord. The term hydromyelia is sometimes used interchangeably with a closely related condition, syringomyelia (or syringohydromyelia). Syringomyelia (SM) is a condition in which fluid collects in the area of the spinal cord that is outside the central canal. The end result of hydromyelia and syringomyelia is essentially the same: an abnormal cyst (collection of fluid) in the spinal cord that is associated with a wide range of neurological complaints and signs. For simplicity, the term syringomyelia is used to refer to a fluid-filled cyst in the spinal cord that is inside or outside of the central canal.

spinal cord results in pain, weakness, and loss of sensation for the affected individual. Syringomyelia may be an isolated finding or may be found in association with a syndrome that disrupts the flow of cerebral spinal fluid (CSF), such as the Arnold-Chiari malformation or the DandyWalker malformation. The earliest known description of cystic dilatation (widening) of the spinal cord dates back to the sixteenth century. The terms syringomyelia and hydromyelia were first used in published reports in 1827 and 1859, respectively.

Demographics Syringomyelia occurs across all races and ethnic groups and affects both children and adults. Although syringomyelia usually appears in midlife, it can occur at any age. Estimates of the incidence of syringomyelia vary and range from 1 in 18,000 to as high as 1 in 1,300 people in the United States.

Causes and symptoms The causes of syringomyelia are not well understood. It is thought that syringomyelia occurs when one or more factors interfere with the normal development of the spinal canal during formation of the embryo or when factors such as trauma to the spinal cord, infection, or a mass (such as tumor) interfere with the fluid dynamics in the spinal cord. Arnold-Chiari malformation is the leading cause of syringomyelia. Syringomyelia occurs in as many as onequarter of people who have a spinal cord injury. Various theories have been postulated to explain how movement of cerebrospinal fluid and pressure in the central nervous system (the brain and spinal cord) interact to produce this defect. In some cases, genetic factors may play a role in the development of this condition. The symptoms of syringomyelia can be quite variable and depend upon the location and extent of the cyst. Common symptoms of syringomyelia in affected individuals include: • extreme pain or “heavy” feeling in the neck; shoulders are usually numb • headaches • leg or hand weakness • numbness or loss of sensation in the hands and feet

Description

• problems with walking

Syringomyelia is a variable condition in which the symptoms depend on the location and extent of the cavitation (hollowing out) of the cord. Over time, the expansion and elongation of the fluid-filled cavity (or cyst) can destroy the center of the spinal cord. This damage to the 434

• loss of bowel and bladder control • spasticity and paralysis of the legs • visual disturbances • ataxia

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Dandy-Walker malformation A complex structural abnormality of the brain frequently associated with hydrocephalus, or accumulation of excess fluid in the brain. Abnormalities in other areas of the body may also be present. Individuals with Dandy-Walker malformation have varying degrees of mental handicap or none at all.

• speech problems • scoliosis (curvature of the spine)

Diagnosis Diagnosis of syringomyelia is based on neurological exam and results of neuroradiological imaging studies. The neurological exam of an affected individual will show loss of sensation in the hands, balance problems, decreased strength, difficulty walking or an abnormal gait, and abnormal reflexes. Some people with no symptoms or mild symptoms are diagnosed with syringomyelia incidentally in the course of evaluation for another condition. Imaging studies used to diagnose syringomyelia include magnetic resonance imaging (MRI), CINE MRI (a type of MRI that shows the flow of cerebrospinal fluid), and electromyography (EMG). In some cases it may be technically difficult to distinguish hydromyelia from syringomyelia.

Treatment Currently, there is no cure for syringomyelia. Neurosurgery is the primary method of treatment for this condition. Surgery tends to be reserved for those individuals with moderate or severe neurological problems. The goal of the various neurosurgical techniques is to restore normal flow of cerebral spinal fluid. There are four main categories of procedures: • decompression procedures • laminectomy and syringostomy • terminal ventriculostomy • percutaneous aspiration Surgical interventions for syringomyelia have limitations and carry risks for potentially severe complications. The decision to operate is generally based on the severity of symptoms and the findings on MRI or other imaging studies. Patients are followed closely after surgery for signs of further neurological impairment. Some patients will need to undergo more than one surgery.

Management of syringomyelia requires a multidisciplinary approach. In addition to the patient’s primary health care professionals, medical professionals involved in the care of patients with syringomyelia generally include a neurologist and a neurosurgeon. Additional specialists in pain management and rehabilitation may also be needed.

Recovery and rehabilitation Patients with syringomyelia may require a wide range of rehabilitation services including physical therapy, occupational therapy, and speech therapy to help them compensate for weakness and loss of function. Chronic pain can pose a significant problem for some patients. Management of chronic pain may include prescription and non-prescription medications, physical therapy, occupational therapy, medical procedures such as nerve blocks or trigger point injections, psychological therapy, and chiropractics.

Clinical trials As of early 2004, there were three clinical trials for patients with syringomyelia, all of which are sponsored by the National Institute of Neurological Disorders and Stroke (NINDS). There is a study (Study and Surgical Treatment of Syringomyelia) to establish the mechanism(s) of progression of primarily spinal syringomyelia (PSS). More information on this study can be obtained at http:// clinicalstudies.info.nih.gov/detail/A_2001-N-0085.html or by contacting the patient recruitment and public liaison office at (800) 411-1222 or [email protected]. In another study (Establishing the Physiology of Syringomyelia), researchers would like to learn more about how the CSF pressure and flow contribute to the progression of syringomyelia. More information can be obtained at http:// clinicalstudies.info.nih.gov/detail/A_1992-N-0226.html or by contacting the patient recruitment and public liaison office. Finally, there is a study (Genetic Analysis of the Chiari I Malformation) whose purpose is to better understand the genetic factors related to the Chiari I malformation. More information can be found at http://clinicalstudies.info.nih. gov/detail/A_2000-N-0089.html or by contacting the patient recruitment and public liaison office. There is also an ongoing genetic research study for Chiari type I malformation and syringomyelia (CMI/S) to determine whether or not there is a genetic component to CMI/S. Interested patients and families may find more information at the Center for Human Genetics at Duke University at http://wwwchg.mc.duke.edu/patients/cms.html or by contacting the center at (800) 283-4316 or syringo@dnadoc. mc.duke.edu.

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Hydromyelia

Key Terms

Treatment team

Hydromyelia The widened spinal cord canal associated with hydromyelia. (Custom Medical Stock Photo. All Rights Reserved.)

Prognosis The course of syringomyelia is not well defined. Some untreated patients will experience a spontaneous remission of symptoms. Among treated patients, some will have a permanent end to their neurological deficits whereas others will only experience temporary relief of symptoms. Long-term studies of affected patients are needed to better understand the natural history and prognosis of this condition. Resources BOOKS

Graham, D. I., and P. L. Lantos, eds. Greenfield’s Neuropathology, volume I, 7th edition. London: Arnold, 2002. Parker, James N., MD, and Philip M. Parker, PhD, eds. The Official Parent’s Sourcebook on Syringomyelia: A Revised and Updated Directory for the Internet Age. San Diego, CA: ICON Health Publications, 2002. Klekamp, Joerg, and Madjid Samii. Syringomyelia: Diagnosis and Treatment, 1st edition. New York: Springer Verlag, 2001. PERIODICALS

Caldarelli, M., and C. Di Rocco. “Diagnosis of Chiari I Malformation and Related Syringomyelia: Radiological 436

and Neurophysiological Studies.” Child’s Nervous System 53 (March 2004): epublication, ahead of print. Kyoshima K., and E. I. Bogdanov. “Spontaneous Resolution of Syringomyelia: Report of Two Cases and Review of the Literature.” Neurosurgery 53 (Sept 2003): 762–9. Wisoff, J. H. “Hydromyelia: A Critical Review.” Child’s Nervous System 4 (1988): 1–8. WEBSITES

American Syringomyelia Alliance Project, Inc. Home Page. (June 2, 2004). . Chiari and Syringomyelia News Home Page. (June 2, 2004). . The National Institute of Neurological Disorders and Stroke (NINDS). Hydromyelia Information Page. (June 2, 2004). . The National Institute of Neurological Disorders and Stroke (NINDS). Syringomyelia Information Page. (June 2, 2004). . ORGANIZATIONS

American Syringomyelia Alliance Project, Inc. P. O. Box 1586, Longview, TX 75606-1586. (903) 236-7079 or (800) ASAP-282; Fax: (903) 757-7456. [email protected]. .

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Hypersomnia

American Chronic Pain Association (ACPA). P.O. Box 850, Rocklin, CA 95677-0850. (916) 632-0922 or (800) 5333231; Fax: (916) 632-3208. [email protected]. . National Spinal Cord Injury Association. 6701 Democracy Blvd. #300-9, Bethesda, MD 20817. (301) 214-4006 or (800) 962-9629; Fax: (301) 881-9817. [email protected]. .

Dawn J. Cardeiro, MS, CGC

Hypercortisolism see Cushing syndrome

❙ Hypersomnia Definition

Hypersomnia refers to a set of related disorders that involve excessive daytime sleepiness.

Description There are two main categories of hypersomnia: primary hypersomnia (sometimes called idiopathic hypersomnia) and recurrent hypersomnia (sometimes called recurrent primary hypersomnia). Both are characterized by the same signs and symptoms and differ only in the frequency and regularity with which the symptoms occur. Primary hypersomnia is characterized by excessive daytime sleepiness over a long period of time. The symptoms are present all, or nearly all, of the time. Recurring hypersomnia involves periods of excessive daytime sleepiness that can last from one to many days, and recur over the course of a year or more. The primary difference between this and primary hypersomnia is that persons experiencing recurring hypersomnia will have prolonged periods where they do not exhibit any signs of hypersomnia, whereas persons experiencing primary hypersomnia are affected by it nearly all the time. One of the best documented forms of recurrent hypersomnia is Kleine-Levin syndrome, although there are other forms as well. There are many different causes for daytime sleepiness that are not considered hypersomnia, and there are many diseases and disorders in which excessive daytime sleepiness is a primary or secondary symptom. Feelings of daytime sleepiness are often associated with the use of common substances such as caffeine, alcohol, and many medications. Other common factors that can lead to excessive daytime sleepiness that is not considered hypersomnia include shift work and insomnia. Shift work can disrupt the body’s natural sleep rhythms. Insomnia can

A colored positron emission tomography (PET) scan of the human brain during deep, non-REM sleep; the brain is active but not as active as during REM sleep. Active areas are red and yellow, inactive areas are blue. (© Hank Morgan/ Science Source/Photo Researchers, Inc. Reproduced by permission.)

cause excessive daytime sleepiness because of lack of nighttime sleep, and is a separate disorder.

Demographics Hypersomnia is an uncommon disorder. In general, 5% or fewer of adults complain of excessive sleepiness during the daytime. That does not mean all those who complain of excessive sleepiness have hypersomnia. There are many other possible causes of daytime sleepiness. Of all the people who visit sleep clinics because they feel they are too sleepy during the day, only about 5–10% are diagnosed with primary hypersomnia. Kleine-Levin syndrome is present in about three times more males than females, but it is a very rare syndrome. Hypersomnia generally appears when the patient is between 15 and 30 years old. It does not begin suddenly, but becomes apparent slowly, sometimes over years.

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Causes and symptoms People experiencing hypersomnia do not get abnormal amounts of nighttime sleep. However, they often have problems waking up in the morning and staying awake during the day. People with hypersomnia nap frequently, and upon waking from the nap, do not feel refreshed. Hypersomnia is sometimes misdiagnosed as narcolepsy. In many ways the two are similar. One significant difference is that people with narcolepsy experience a sudden onset of sleepiness, while people with hypersomnia experience increasing sleepiness over time. Also, people with narcolepsy find daytime sleep refreshing, while people with hypersomnia do not. People with Kleine-Levin syndrome have symptoms that differ from the symptoms of other forms of hypersomnia. These people may sleep for 18 or more hours a day. In addition, they are often irritable, uninhibited, and make indiscriminate sexual advances. People with KleineLevin syndrome often eat uncontrollably and rapidly gain weight, unlike people with other forms of hypersomnia. This form of recurrent hypersomnia is very rare. The causes of hypersomnia remain unclear. There is some speculation that in many cases it can be attributed to problems involving the hypothalamus, but there is little evidence to support that claim.

Diagnosis Hypersomnia is characterized by excessive daytime sleepiness, and daytime naps that do not result in a more refreshed or alert feeling. Hypersomnia does not include lack of nighttime sleep. People experiencing problems with nighttime sleep may have insomnia, a separate sleep disorder. In people with insomnia, excessive daytime sleepiness may be a side effect. The Diagnostic and Statistical Manual of Mental Disorders which presents the guidelines used by the American Psychiatric Association for diagnosis of disorders, states that symptoms must be present for at least a month, and must interfere with a person’s normal activities. Also, the symptoms cannot be attributed to failure to get enough sleep at night or to another sleep disorder. The symptoms cannot be caused by another significant psychological disorder, nor can they be a side effect of a medicinal or illicit drug or a side effect of a general medical condition. For a diagnosis of recurrent hypersomnia, the symptoms must occur for at least three days at a time, and the symptoms have to be present for at least two years.

Treatment team A number of specialists deal with sleep problems, including internal medicine physicians, psychiatrists, neurologists, and sleep disorder specialists. 438

Key Terms Hypothalamus A part of the forebrain that controls heartbeat, body temperature, thirst, hunger, blood pressure, blood sugar levels, and other functions. Narcolepsy A disorder characterized by frequent and uncontrollable attacks of deep sleep.

Treatments There have been some attempts at using drugs to treat hypersomnia. No substantial body of evidence supports the effectiveness of these treatments. Stimulants are not generally recommended to treat hypersomnia as they treat the symptoms but not the base problem. Some researchers believe that treatment of the hypothalamus may be a possible treatment for hypersomnia.

Prognosis Kleine-Levin syndrome has been reported to occasionally resolve by itself around middle age. Except for that syndrome, hypersomnia is considered both a lifelong disorder and one that can be significantly disabling. There is no body of evidence that concludes there is a way to treat the majority of hypersomnia cases successfully. Resources BOOKS

Aldrich, Michael S. Sleep Medicines. New York: Oxford University Press, 1999. American Psychiatric Association Diagnostic and Statistical Manual of Mental Disorders. 4th edition, text revised. Washington DC: American Psychiatric Association, 2000. Chokroverty, Susan, ed. Sleep Disorders Medicine: Basic Science, Technical Considerations, and Clinical Aspects. 2nd ed. Boston: Butterworth-Heinemann, 1999. Sadock, Benjamin J. and Virginia A. Sadock, eds. Comprehensive Textbook of Psychiatry. 7th edition, vol. 2. Philadelphia: Lippincott Williams and Wilkins, 2000. Thorpy, Michael J, ed. Handbook of Sleep Disorders. New York: Marcel Dekker Inc, 1990. PERIODICALS

Boris, Neil W., Owen R. Hagina, Gregory P. Steiner. “Case Study: hypersomnolence and precocious puberty in a child with pica and chronic lead intoxication.” Journal of the American Academy of Child and Adolescent Psychiatry 35, no. 8 (August 1996): 1050-1055. National Center on Sleep Disorders Research Working Group, Bethesda, Maryland. “Recognizing Problem Sleepiness in Your People.” American Family Physician (February 15, 1999): 937-38.

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American Academy of Sleep Medicine. 6301 Bandel Road NW, Suite 101, Rochester, MN 55901. (507) 287-6006. .

Tish Davidson, AM Rosalyn Carson-DeWitt, MD

Hypertonia see Spasticity

❙ Hypotonia Definition

Hypotonia means “low tone,” and refers to a physiological state in which a muscle has decreased tone, or tension. A muscle’s tone is a measure of its ability to resist passive elongation or stretching.

Description Hypotonia is more a description than a diagnosis. It is most often seen in newborns (congenital) and infants, but it may persist through adolescence into adulthood. Another name for infantile hypotonia is “floppy baby syndrome.” This refers to the tendency of a hypotonic infant’s arms, legs, and head to “flop,” or dangle loosely, when they are picked up or moved. In the past, the term “benign congenital hypotonia” was used for many cases in which no obvious cause for the hypotonia could be detected. Better diagnostic techniques and increased knowledge of neuromuscular disorders, however, have resulted in much less frequent use of this term.

Demographics Hypotonia is the most common muscular abnormality seen in neonatal (newborn) neurological disorders. It affects males and females equally, and shows no preponderance in any particular ethnic group or race. An increase in the occurrence of hypotonia in recent years is correlated with increased survival rates of infants born significantly premature, since these children are at increased risk for neurological problems.

Causes and symptoms The causes of hypotonia are varied and numerous. Some involve trauma to, or diseases of, the brain or spinal cord (CNS), while others affect the peripheral nerves, neuromuscular junction, or the muscles themselves. A disorder of the nervous system is a neuropathy, while a muscle disease is a myopathy. A neuromuscular condition is one

Hypotonia

ORGANIZATIONS

Key Terms Congenital Present at birth. Muscle tone Also termed tonus; the normal state of balanced tension in the tissues of the body, especially the muscles. Myopathy Any abnormal condition or disease of muscle tissue, characterized by muscle weakness and wasting. Neuromuscular Involving both the muscles and the nerves that control them. Neuropathy A disease or abnormality of the peripheral nerves (the nerves outside the brain and spinal cord). Major symptoms include weakness, numbness, paralysis, or pain in the affected area.

in which a neurological disorder results in associated muscular symptoms. CNS trauma and infection are perhaps the most common cause of hypotonia, both in infants and in children. Insult to the brain may occur prenatally (before birth), perinatally (around the time of birth), or postnatally (after birth). Prenatal CNS damage may be caused by certain maternal/fetal infections, maternal diseases, problems with the placenta or umbilical cord, or maternal use of harmful substances such as alcohol or certain drugs. Most congenital brain malformations, however, have no discernible cause and are likely due to chance maldevelopment of a very complex organ. Perinatal asphyxia/hypoxia (lack of oxygen to the baby’s brain) occurs less frequently than is commonly believed, but does present a risk for CNS damage that can result in hypotonia. The greatest risk for asphyxia/hypoxia is from complicated and/or premature deliveries. Infants who are born healthy may sustain postnatal brain injury if they suffer from breathing difficulties, develop an infection in the lining of the brain (see Meningitis), or suffer some other type of physical trauma or abuse. While it is less common, hypotonia may develop in an adult. This is again most often the result of CNS trauma or disease, usually affecting the cerebellum. The primary function of the cerebellum is control of balance and coordination, including maintaining passive tension/tone of the muscles, such as muscular control required for standing. A number of different genetic disorders are associated with hypotonia, and may affect the nerves (and by extension the muscles), or the muscles only. Most genetic conditions are generalized (affecting multiple muscle groups) and progressive. Some genetic conditions are hereditary

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Hypotonia A six-week-old baby girl is held horizontally by the trunk in a test for hypotonia, sometimes called “floppy infant syndrome.” (Saturn Stills / Science Photo Library.)

(autosomal recessive or X-linked recessive) and some are sporadic (chromosomal disorders). Hereditary conditions would typically imply a 25% recurrence risk for siblings on the affected child, while the chance for another child with the same chromosomal abnormality is usually about 2–3%. In addition to low muscle tone, infants with hypotonia may also exhibit excessive flexibility of the joints (hypermobility), decreased deep tendon reflexes (e.g., tapping the knee joint produces little or no muscle jerk), and difficulties with sucking and swallowing. Children in whom hypotonia persists often show delays in gross motor skills such as sitting up, crawling, and walking. They may also have difficulties with coordination and exhibit speech delays. In some cases, symptoms may persist into adulthood. Hypotonia itself is not associated with decreased intellectual development, but the underlying cause may pose significant risks for developmental delay and mental retardation.

Diagnosis Diagnosis of the cause of hypotonia may involve a number of different medical methods, procedures, and tests. These include: 440

• A complete prenatal (before birth) and perinatal (around the time of birth) history. Along with this a complete family medical history should be obtained. • A physical examination to determine the degree of hypotonia and the muscles affected • An electromyelograph (EMG), measures muscle response to electrical stimulation • A nerve conduction velocity (NCV), measures a nerve’s ability to transmit electrical impulses to and from the muscle • Electroencephalogram (EEG), a test that measures the electrical activity in the brain • A muscle biopsy to analyze the microscopic structure of affected muscle • Biochemical tests on muscle tissue and blood • Genetic tests to look for possible sporadic (chance occurrence) or hereditary genetic errors affecting the brain, nerves, and/or muscles • Imaging studies (CT scan or MRI) of the brain and spinal cord

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Treatment team Along with normal pediatric care, specialists who may be involved in the care of a child with hypotonia include developmental pediatricians (specialize in child development), neurologists, neonatologists (specialize in the care of newborns), geneticists, occupational therapists, physical therapists, speech therapists, orthopedists, pathologists (conduct and interpret biochemical tests and tissue analysis), and specialized nursing care. Depending on the cause and progression of hypotonia, treatment and evaluation may be needed throughout life.

Treatment Unlike the wide array of potential causes of hypotonia, treatment options for low muscle tone are somewhat limited. In very severe cases, treatment may be primarily supportive, such as mechanical assistance with basic life functions like breathing and feeding, physical therapy to prevent muscle atrophy and maintain joint mobility, and measures to try and prevent opportunistic infections such as pneumonia. Treatments to improve neurological status might involve such things as medication for a seizure disorder, medicines or supplements to stabilize a metabolic disorder, or surgery to help relieve the pressure from hydrocephalus (increased fluid in the brain). If the neurologic condition is untreatable, physical and occupational therapy may help to improve muscle tone, strength, and coordination.

Recovery and rehabilitation In all cases, frequent or periodic monitoring of muscle tone and performance, along with neurological status, should be done to determine if the hypotonia is worsening, static, or improving. Effective recovery and rehabilitation can only be achieved if an accurate status of the condition is known. Since muscle weakness often accompanies hypotonia, efforts to improve muscle strength may also improve low muscle tone. Some individuals with persistent symptoms may need assistance with mobility, such as a walker or wheelchair. Occupational and physical therapy can assist individuals in developing alternative methods for accomplishing some everyday tasks they may find difficult. Speech therapy is primarily directed at young children to help them develop language skills early, but can be

beneficial at any age if the muscles of the face and throat are hypotonic.

Clinical trials Prognosis Determining a prognosis depends on determining a diagnosis for hypotonia. Some genetic conditions are fatal in infancy, while others result in permanent disability and mental retardation. For those few genetic metabolic disorders that are treatable, improvement may be dramatic, or minimal. Outcomes for hypotonia caused by CNS trauma or infection depend on the severity of neurologic damage. Mild trauma obviously has the best chance for improvement and recovery, but even significant neurologic deficits may improve over time. Most individuals with a nongenetic form of hypotonia will improve to some degree. From a broad perspective, some individuals with hypotonia will respond very little or not at all to any treatment method attempted, while in others the condition will resolve on its own; each case is unique. Resources BOOKS

Volpe, Joseph J. Neurology of the Newborn, 4th ed. Philadelphia: W. B. Saunders Company, 2001. Weiner, William J. and Christopher G. Goetz, eds. Neurology for the Non-Neurologist, 4th ed. Philadelphia: Lippincott Williams & Wilkins, 1999. OTHER

The National Institute of Neurological Disorders and Stroke. NINDS Hypotonia Information Page. (March 26, 2003). . Thompson, Charlotte E. “Hypotonia, Benign Congenital” National Organization for Rare Disorders Report. (2003). . ORGANIZATIONS

March of Dimes Birth Defects Foundation. 1275 Mamaroneck Avenue, White Plains, NY 10605. 888-663-4637; Fax: 914-428-8203. . Muscular Dystrophy Association. 3300 East Sunrise Drive, Tucson, AZ 85718-3208. 800-572-1717; Fax: 520-5295300. . National Institute of Child Health and Human Development Clearinghouse. PO Box 3006, Rockville, MD 20847. 800-370-2943. . National Organization for Rare Disorders (NORD) . P.O. Box 1968, 55 Kenosia Avenue, Danbury, CT 06813-1968. 203-744-0100; Fax: 203-798-2291. .

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Hypotonia

Determining which tests to use depends on the clinician’s judgment of what is most likely to be the underlying cause of the hypotonia. This in turn is based upon the history and physical findings. In some cases, different doctors will order different tests based upon their area of expertise. There is always a possibility that a diagnosis will not be determined. The term for hypotonia without a diagnosis is “idiopathic,” which literally means “unknown cause.”

Hypoxia

❙ Hypoxia

Key Terms

Definition

Hypoxia generally refers to a lack of oxygen in any part of the body. In a neurological context, it refers to a reduction of oxygen to the brain despite adequate amounts of blood.

Depolarization Occurs when a neuron exchanges ions, causing an influx of sodium and calcium inside the cell and an efflux of potassium out of the cell.

Description A decrease in oxygen supply to the brain can occur due to choking, strangling, suffocation, head trauma, carbon monoxide poisoning, cardiac arrest, and as a complication of general anesthesia. A failure to deliver oxygen and glucose to the brain causes a cascade of abnormal events. The extent of damage is directly proportional to the severity of the injury. The severity of cerebral ischemia, a low-oxygen state caused by arterial obstruction or lack of blood supply, and the duration of blood-flow loss in the brain determine the extent of brain damage. The neurons can suffer temporary dysfunction, or there may be irreversible damage to nerve cells that are sensitive to minute changes in oxygen levels. Severe damage involving extensive areas can occur (cerebral infarction). Cerebral hypoxia/ischemia can be caused by a broad spectrum of diseases that affect the cardiovascular pumping system or the respiratory system. There are four types of disorders to consider: focal cerebral ischemia, global cerebral ischemia, diffuse cerebral hypoxia, and cerebral infarction. Focal cerebral ischemia Focal cerebral ischemia (FCI) is often results from a blood clot in the brain. The blood flow in the affected area is reduced. The reduction could be severe or mild but usually FCI causes irreversible injury to sensitive neurons. The clinical signs and symptoms last approximately 15–30 minutes. Global cerebral ischemia Global cerebral ischemia (GCI) is a serious condition caused by ventricular fibrillation or cardiac asystole, which stops all blood flow to the brain. If the GCI lasts more than five to ten minutes, then it is likely the person will have suffered a loss of consciousness that makes recovery doubtful. Diffuse cerebral hypoxia Diffuse cerebral hypoxia (DCH) is limited to conditions that cause mild to moderate hypoxemia, or low arterial-oxygen content due to deficient blood oxygenation. Pure cerebral hypoxia causes cerebral dysfunction but not irreversible brain damage. Pure cerebral hypoxia can 442

occur due to pulmonary disease, altitude sickness, or severe anemia. Cerebral infarction Cerebral infarction (CI) is a severe condition caused by a focal vascular occlusion in an area of the brain. This causes an area of destruction resulting from a lack of oxygen delivery. Pathology of cerebral ischemia Lack of oxygen causes neurons in the brain to die in several ways. Autolysis can occur, which results from the digestion of nerve tissues by enzymes. Cerebral infarction causes the death of neurons; transient cessation of the cerebral circulation for a few minutes causes selective areas of ischemic necrosis. This type of necrosis is especially evident in highly vulnerable neurons that are sensitive to abrupt oxygen deprivation. More prolonged periods of moderate-to-severe hypoxemia or carbon monoxide poisoning can cause a loss of the outer sheath of neurons. Molecular mechanisms of cerebral hypoxia In cases of severe ischemia to brain tissue, the tissue loses structural integrity within a few seconds or a few minutes. Soon after there is an abnormal exchange of ions in neurons through a process called depolarization; this is characterized by an influx of sodium and calcium ions inside the neuron, and a simultaneous efflux of potassium ions outside the neuron. Cerebral edema Cerebral edema refers to abnormal increases in water content in the brain and occurs with all types of cerebral ischemia and hemorrhagic stroke. Increased water retention in the brain causes an increase in intracranial pressure. This pressure causes the brain to be pushed against the skull, resulting in neurologic deterioration and death due to herniation. Cerebral edema and herniation of the brain is the cause of death for approximately 75% of all fatal stroke victims and 33% of fatalities for all ischemic events to the brain.

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Symptoms vary depending on the severity of damage. Symptoms of mild cerebral hypoxia can include poor judgment, memory loss, inattentiveness, and a decrease in motor coordination. In more severe cases, there can be permanent neurologic deficits, coma, seizures, or death.

Treatment Treatment depends on the cause and availability of equipment. Treatment is urgent and includes basic and advanced life-support measures. It is important to maintain breathing, dispense intravenous fluids and medications, and maintain stability with blood products and medications that control blood pressure and seizures. The outlook depends on the extent of cerebral ischemia.

Resources BOOKS

Goldman, Lee, et al. Cecil’s Textbook of Medicine, 21st ed. Philadelphia: W. B. Saunders Company, 2000. ORGANIZATIONS

Brain Injury Association. 8201 Greensboro Drive, Suite 611, McLean, VA 22102. (703) 761-0750 or (800) 444-6443; Fax: (703) 761-0755. [email protected]. . National Rehabilitation Information Center (NARIC). 4200 Forbes Boulevard, Suite 202, Lanham, MD 20706-4829. (301) 562-2400 or (800) 346-2742; Fax: (301) 562-2401. [email protected]. .

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Laith Farid Gulli, MD Robert Ramirez, DO

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Symptoms

I ❙ Idiopathic neuropathy Definition

Idiopathic neuropathy is a disorder that affects the peripheral nerves and has no identifiable primary cause. According to this definition, a third of all neuropathies can be classified as idiopathic neuropathies.

Demographics Idiopathic peripheral neuropathies occur typically in middle-aged and elderly individuals and affect two million people in the United States. However, epidemiological studies are scarce. Available studies suggest that 2.4–8% of all adults may have some form of neuropathy. The most common cause is diabetes, which accounts for approximately one-third of all neuropathies; the remaining twothirds are idiopathic and of all other known causes.

Description The nervous system is divided into two parts: the central nervous system (CNS) and the peripheral nervous system (PNS). The brain and spinal cord compose the CNS, and the nerves that lead to or branch off the CNS compose the PNS. Peripheral neuropathies encompass a wide range of disorders in which peripheral nerves are damaged. It may also be referred to as peripheral neuritis (inflammation of peripheral nerves), or if many nerves are involved, the terms polyneuropathy or polyneuritis may be used. Some of the causes of peripheral neuropathies are common, such as diabetes, and others are extremely rare, such as acrylamide poisoning and certain inherited disorders. Sometimes peripheral neuropathies seem to happen for no particular reason. In such cases, they are called idiopathic, meaning of unknown cause. Idiopathic neuropathies can be classified as idiopathic mononeuropathies and polyneuropathies. An idiopathic mononeuropathy, or radiculopathy, refers to the involvement of a single nerve or nerve root, respectively. A polyneuropathy usually refers to the diffuse involvement of peripheral nerves. Clinical manifestations depend on the type and distribution of the affected nerve population, the degree to which they are damaged, and the course of the disease. For example, if a motor nerve is damaged, the neuropathy manifests as weakness and muscle atrophy, whereas if the damage involves sensory nerves, it may cause loss of sensation, pain, and sensory ataxia.

Causes and symptoms There are no known causes for idiopathic neuropathies, and therefore they are considered primary diseases. If a cause is detected, then the neuropathy is secondary to that, and not idiopathic. Nonetheless, there are many different peripheral neuropathies, among them the idiopathic type, which demonstrates the functional diversity of PNS activities. Symptoms may involve sensory, motor, or autonomic functions. Symptoms are classified based on the affected nerve type and the duration of disease development. Acute development refers to symptoms that have appeared within days, and subacute refers to those that have evolved over a number of weeks. Early chronic symptoms are those that take months to a few years to develop, and late chronic are the ones that have been present for several years. Most times, the first symptoms include numbness, tingling and pain, unsteadiness when standing or walking, muscle weakness (including weak ankles), or cramps and faintness. Depending on the affected group of nerves, secondary symptoms may vary from loss of vibratory sensation at the toes to loss of temperature perception to muscle atrophy.

Diagnosis Several tests are necessary in order to eliminate all the possible primary causes of the disease, after which idiopathic neuropathy may be defined as a diagnosis; hence it

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Treatment

Key Terms Electromyography A test that detects electric activity in muscle that is used to determine nerve or muscle damage. Idiopathic A disease or condition of unknown cause or origin. Neuropathy A disease or condition of the nervous system or a nerve. Paresthesia Abnormal numbness or tingling sensation, whether spontaneous or evoked.

is a diagnosis of exclusion. The patient’s history plays a major role in the diagnosis and has to include all symptoms, date of onset, duration, extension of affected area, and amount of discomfort and pain. Specific details about tingling, numbness, weakness, or other symptoms are also very important. During the neurological evaluation, a physical examination will test for loss of vibratory sensation, ankle jerks, and other reflexes. Sensations in the feet and hands will be evaluated. The purpose of these tests is to assess the neurological function, including muscle strength, autonomic nerve function, and the ability to feel different sensations. An electromyography may be performed to measure the electrical activity of muscles and nerves. Through this measurement, the physician is able to detect the presence of nerve damage, the possible cause of the damage, and if damaged nerves are responding to treatment. If necessary, other tests can be used, such as a nerve biopsy, a lumbar puncture (spinal fluid analysis), and magnetic resonance imaging (MRI), which creates images of the body and its organs that may be used in the confirmation or exclusion of disorders with similar symptoms. Blood tests are commonly employed to check for vitamin deficiencies, toxic elements, and evidences of abnormal immune responses. The quantitative sensory test (QST) is a method used to assess damage to small nerve endings (temperature changes) and large nerve endings (vibration changes). Autonomic tests measure how autonomic nerves respond to stimulation. Data collected will indicate if the autonomic nervous system is functioning adequately, or if nerve damage is present. The quantitative sudomotor axon reflex test (QSART) is used to assess small nerve fibers linked to sweat glands. QSART is used to diagnose painful, small fiber neuropathies when nerve conduction test results are normal.

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Treatment for idiopathic neuropathies is mostly symptomatic, including pain therapy for paresthesias, physical and occupational therapy to help improve mobility and function, supportive measures to maintain blood pressure, and bowel and bladder function if the autonomic system is involved. Treatment options for reducing pain include medication, injection therapy, and physical therapy. Surgery may be needed to treat some causes of neuropathy (e.g., carpal tunnel syndrome, radiculopathy). Because analgesics (aspirin, ibuprofen) are usually ineffective against pain caused by neuropathy, treatment often involves medications that target nerve cells. Antidepressants such as gabapentin and amitriptyline are usually the first medications prescribed. Side effects of these drugs include drowsiness, dizziness, low blood pressure, and fatigue. Other medications include anticonvulsants (carbamazepine and lamotrigine), local anesthetics (lidocaine), and antiarrhythmics (mexiletine). Anticonvulsants may cause low white blood cell counts, nausea, vomiting, and dizziness. Side effects of lidocaine and mexiletine include nervousness, lightheadedness, drowsiness, and double vision. Topical treatment with capsaicin cream may be prescribed for patients with focal neuropathy. Capsaicin causes stinging upon application and is often combined with a local anesthetic to reduce this side effect. Injection therapy involves injecting a nerve block (lidocaine) into the area surrounding affected nerves, preventing the nerve from carrying impulses to the brain and temporarily reducing symptoms. Injection therapy is often used with other treatments such as medication and physical therapy. Discontinuing medication or exposure to toxic substances may eliminate neuropathy caused by drugs or toxins. Vitamin supplements may be used to treat nutritional neuropathy. Physical therapy, including exercise, massage, and heat, and acupuncture (insertion of fine needles into specific points on the body) may be used to treat symptoms. Treatment for the causes of neuropathy include antibiotics or antiviral agents for infectious neuropathies, immunomodulating agents for immune-mediated neuropathies, improved glycemic control for diabetic neuropathies, and surgery for compressive neuropathies. Over-the-counter pain relievers can help treat mild-tomoderate pain associated with peripheral neuropathy. There are two main types of over-the-counter pain relievers: acetaminophen and nonsteroidal anti-inflammatory

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Support groups often help patients cope with feelings of isolation and frustration and improve their quality of life.

Clinical trials As of 2004, there were no clinical trials for idiopathic neuropathies; however, there are several that aim at other types of neuropathies, such as the diabetic neuropathy.

Prognosis Prognosis and complications depend on the type and severity of the neuropathy. Idiopathic neuropathies range from a reversible problem to a potentially fatal complication. In the best-case scenario, a damaged nerve regenerates. Nerve cells cannot be replaced if they are killed, but they are capable of recovering from damage. The extent of recovery is tied to the extent of the damage, to the patient’s age, and to the general health status. Recovery can take weeks to years due to the slow neuronal regrowth rate. Full recovery may not be achieved in some cases.

Special concerns Complementary and alternative therapies can help manage pain caused by neuropathies. These are noninvasive, drug-free treatments that support natural body healing. They may be used alone or combined with other medications and treatments. Some alternative therapies are biofeedback, acupuncture, and relaxation techniques. Resources PERIODICALS

Donofrio, P. D. “Immunotherapy of Idiopathic Inflammatory Neuropathies.” Muscle Nerve 28 (2003): 273–292. Lacomis, D. “Small-Fiber Neuropathy.” Muscle Nerve 26 (2002): 173–188. Low, P. A., S. Vernino, and G. Suarez. “Autonomic Dysfunction in Peripheral Nerve Disease.” Muscle Nerve 27 (2003): 646–661. Kelkar, P., W. R. Mcdermott, and G. J. Parry. “SensoryPredominant, Painful, Idiopathic Neuropathy: Inflammatory Changes in Sural Nerves.” Muscle Nerve 26 (2002): 413–416.

OTHER

Neurology Channel. Neuropathy. January 4, 2004 (April 4, 2004). . The Jack Miller Center for Peripheral Neuropathy, University of Chicago. Idiopathic Neuropathy. January 4, 2004 (April 4, 2004). . ORGANIZATIONS

The Jack Miller Center for Peripheral Neuropathy, University of Chicago. 5841 South Maryland Avenue, MC2030, Chicago, IL 60637. (773) 702-5546. [email protected]. . The Neuropathy Association. 60 East 42nd Street, New York, NY 10165-0999. (212) 692-0662 or (800) 247-6968; Fax: (212) 696-0668. [email protected]. .

Bruno Marcos Verbeno Iuri Drumond Louro

Immune-mediated encephalomyelitis see Acute disseminated encephalomyelitis

❙ Inclusion body myositis Definition

Inclusion body myositis (IBM) is an inflammatory muscle disease characterized by progressive muscle weakness and wasting. The common feature of IBM is the abnormal finding of inclusion bodies, or granular material, in muscle fibers. The onset generally occurs gradually over months or years, and persons often experience falling and tripping as the first symptoms. Inclusion body myositis affects both proximal (closest to the center of the body) and distal (farthest from the center of the body) muscles.

Description Sporadic inclusion body myositis is the most common muscle disease in people aged 50 years and older with an unknown cause. The disease was named in 1971, when scientists noted a case of myositis (muscle inflammation) that showed granular material in muscle fibers called inclusion bodies. The inclusion bodies are now recognized to contain abnormal deposits of amyloid proteins, similar to those found in the brain of patients with Alzheimer’s disease. The deposits may represent a protein product left within the muscle fibers as they degenerate. The onset of IBM is insidious, with symptoms often having been present for more than five years before diagnosis. The course of the disease is progressive over months

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drugs (NSAIDs). Acetaminophen is used to treat mild-tomoderate pain and reduce fever, but it is not very effective at reducing inflammation. Acetaminophen provides relief from pain by increasing the pain threshold. Nonsteroidal anti-inflammatory drugs (NSAIDs) reduce pain, swelling, stiffness, and inflammation. Two drugs in this category, ibuprofen and naproxen, also reduce fever. When these drugs are taken regularly, they build up in the blood to levels that fight pain caused by inflammation and swelling, and also provide general pain relief.

Inclusion body myositis

or years, leading to severe disability. IBM may appear identical to another inflammatory myositis called polymyositis, although differences are clear in more than half of cases. Weakness and impairment of muscle function are the hallmarks of IBM, and weakness distribution is variable, with both proximal (closest to the center of the body) and distal (farthest from the center of the body) muscles affected. Diminished deep-tendon reflexes and wasting (atrophy) of the involved musculature occur. Thus, loss of finger dexterity and grip strength may be present, while falling and tripping appear as the first signs. Patients often suffer from fatigue and reduced tolerance to exertion, and consequently become out of breath easily.

Demographics There are no data currently available for the incidence of IBM internationally, although it has been reported in Europe and Asia. IBM is thought to account for approximately 15–20% of all cases of inflammatory myositis in the United States. Mortality rate (rate of deaths) is difficult to assess, as most people with IBM are older and may die of other coexisting medical problems. There is no race prevalence, but it is uncommon among African Americans. The male/female ratio is 3:1 and most affected individuals are 50 years or older. Nevertheless, IBM does not seem to affect life expectancy.

Causes and symptoms The causes of IBM remain unknown and it is thought to be a multifactorial disease. Aging factors may play an important role as pathogenic (disease-causing) components. Research has been made to establish whether IBM might be influenced by environmental factors. Thus, inflammation may be a secondary component occurring in response to foreign proteins called antigens, such as viral proteins or altered muscle proteins, and perhaps induces an autoimmune response (a reaction of the organism against itself). A possibility that excessive accumulation of certain proteins within muscle fibers can induce inflammation is supported by the findings in transgenic mice studies in which mice were modified to express these human proteins. The results have shown that when synthesizing large amounts of the protein in the muscles, mice developed an age-related motor deficit with muscle inflammation. Also, aging muscle fiber was shown to promote accumulation of abnormal proteins, suggesting an aging-based degenerative process. It has been shown that muscle can secrete this protein and thus, it might cause inflammation by stimulating the immune system to react against the affected muscle.

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Key Terms Autoimmune An immune response by the body against its own tissues or cells. Inclusion bodies Small intracellular bodies found within another intracellular body, characteristic of certain diseases. Myositis Inflammation of a muscle.

The stimulus for excessive amyloid production is unknown, and whether this precedes inflammation, or viceversa, remains to be determined. Genetic causes of IBM have also been proposed, and studies focused on human leukocyte antigen genes that encode for proteins that influence immune response. They were found related to the development of IBM, but their role is not clear. As an acquired process, weakness or impairment of muscle function in the area(s) affected is the primary symptom of IBM. The distribution of weakness is variable, but most muscles are affected, including those in the neck, hip, quadriceps, back, shoulder, wrist, and finger. Many people with IBM notice shrinking, or atrophy, in the arms and thighs as the muscles become weaker. As thighs are affected by atrophy, sudden falls may occur. Lower leg weakness can cause difficulty lifting up the foot, which can lead to tripping. Difficult swallowing, or dysphagia, is a common problem in up to 40% of persons with IBM, and choking may become a problem when ingesting some types of food or liquids. Weakness of facial muscles is sometimes seen. Fatigue and reduced tolerance to exertion are common, and cardiac disease is also present in those with IBM, although its relation to IBM has not been demonstrated. The disease itself does not cause pain; however, weakened muscles can predispose to injuries affecting bones, joints and soft tissues. Elderly patients normally die of other clinical problems rather than of IBM, and most suffer some degree of disability as disease progresses.

Diagnosis The IBM diagnosis is carried out according to clinical features and laboratory studies. The illness lasts longer than six months and the age of onset is greater than 30 years old. People with IBM have considerable quadriceps and wrist and finger flexor weakness. Blood tests show high levels of creatine kinase, a muscle enzyme released by damaged muscle. Electromyography (EMG) can be used to detect the electrical impulses of muscle contraction, which exhibit

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As IBM muscles are damaged, muscle biopsy is the definitive test. In a muscle biopsy, a small sample of the muscle is taken under local anesthesia. Laboratory analysis can identify the inclusion bodies within muscle fibers and the invasion of the damaged tissue by immune cells featuring the inflammation with muscle destruction. This appearance will allow the pathologist and clinician to confirm the diagnosis of IBM. None of the other clinical or laboratory features are mandatory if muscle biopsy features are diagnostic. Muscle biopsy is also important for the exclusion of other neuromuscular diseases. It has been suggested that magnetic resonance imaging (MRI) may be useful detecting active myositis and recognizing selective patterns of muscle involvement in IBM. MRI is also helpful in selecting an appropriate biopsy site. The results of such studies are also useful to guide therapeutic decisions when a biopsy is not possible or the biopsy findings are inconclusive. Because of the imprecise nature of muscle weakness in IBM, a diagnosis is sometimes delayed for years after the onset of weakness. In some patients, the initial biopsy may not disclose the diagnosis, and a second biopsy may be necessary.

Treatment team A neurologist or rheumatologist is the primary consultant for IBM treatment, along with allied health care areas including but not limited to physical therapists and otolaryngologists (ear, larynx, and upper respiratory tract specialists).

Clinical trials No treatment has shown to be effective against IBM; however, new therapies are currently being tested. The National Institute of Neurological Disorders and Stroke (NINDS) is sponsoring a study entitled “Immune Abnormalities in Sporadic Inclusion Body Myositis.” This is an investigative study intended to better define the pathogenesis of IBM. The National Institute of Arthritis and Musculoskeletal and Skin Diseases (NIAMS) is recruiting patients to a study, “Study and Treatment of Inflammatory Muscle Diseases,” which intends to obtain useful material for immunological studies and to sponsor standard therapies for patients. It is likely that in the future more therapeutic trials of drugs in IBM will be organized.

Prognosis IBM generally worsens progressively and slowly. Some observations of stabilizations and remissions, spontaneous or under treatment, have been reported but are usually only temporary.

Special concerns Exercise is generally helpful by getting the most out of diseased muscles. Falls and injuries, however, can cause substantial disability. Patients, therefore, have the difficult task of undertaking regular exercise within their capability, but avoiding injury through accident. Because weakened muscles cannot carry an excessive load, keeping to an ideal weight is helpful. A well-balanced diet is also helpful. Patients with severe inflammation of the muscles may need extra protein to balance their loss. Resources

Treatment Currently, no treatment has been shown to be effective against the different forms of IBM. Some moderate success has been obtained with the drug therapy combination of corticosteroids and methotrexate or human intravenous immunoglobulins. New therapeutic protocols are currently being tested. Physical therapy, occupational therapy, and ergotherapy (treatment of disease by muscular exercise) are commonly prescribed.

Recovery and rehabilitation In most cases of IBM, there is continued deterioration in spite of the treatment reduction of muscle inflammation and immune cells invasion of muscle tissue. Because of the slow progression, any treatment trial should last for at least six months (possibly 12–18 months) to evaluate benefits. Physical therapy and occupational therapy may help patients as disability increases.

BOOKS

Askanas, Valerie, Georges Serratrice, and W. Engel. Inclusion Body Myositis and Myopathies. New York: Cambridge University Press, 1998. Parker, James N., and Philip M. Parker. The Official Patient’s Sourcebook on Inclusion Body Myositis. San Diego: Icon Group International, 2002. PERIODICALS

Mastaglia, F. L., M. J. Garllep, B. A. Phillips, and P. J. Zilko. “Inflammatory Myopathies: Clinical, Diagnostic and Therapeutic Aspects.” Muscle & Nerve (April 2003): 407–425. OTHER

“Inclusion Body Myositis.” The Myositis Association. March 4, 2004 (April 27, 2004). . “NINDS Inclusion Body Myositis Information Page.” National Institute of Neurological Disorders and Stroke. March 4, 2004 (April 27, 2004). .

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a different pattern in IBM patients. Although useful, EMG cannot be taken as a definite diagnosis.

Incontinentia pigmenti

ORGANIZATIONS

Myositis Association of America. 755 Cantrell Ave., Suite C, Harrisonburg, VA 22801. (540) 433-7686; Fax: (540) 4320206. [email protected]. .

Marcos do Carmo Oyama Iuri Drumond Louro, MD, PhD

Neurological problems associated with incontinentia pigmenti occur in about 25% of cases and include cerebral atrophy (deterioration and loss of brain cells), leading to poor muscle control and weakness. Mental retardation and seizures are also similarly present.

❙ Incontinentia pigmenti Definition

Incontinentia pigmenti is a rare genetic disease resulting in a neurocutaneous disorder. Neurocutaneous means that the disorder affects the nervous system and that clinical abnormalities can involve the skin, hair, and teeth of affected individuals.

Description Incontinentia pigmenti patients develop discolored, abnormally pigmented skin that is distributed randomly and asymmetrically. Occasionally, persons with incontinentia pigmenti experience cognitive delays (including mental retardation), but most have normal intelligence. Muscle weakness in one or both sides of the body is also characteristic of the disorder. Incontinentia pigmenti is also known as Bloch-Sulzberger syndrome, as well as incontinentia pigmenti, type 2.

Demographics Incontinentia pigmenti is considered rare, with only about 1,000 affected individuals reported in medical literature. The gene that is defective in this disease is located on the X chromosome and is inherited as a dominant disorder, meaning that each child of an affected mother has a 50% risk of inheriting the faulty gene and the disorder. Most male fetuses affected with incontinentia pigmenti die before birth; more females are affected with the disorder.

Causes and symptoms Incontinentia pigmenti results in defects in the skin, nails, hair, and teeth. The disorder is caused by mutations in the IKBKG gene, located on the X chromosome. This gene encodes a protein that is important during human development. Approximately 80% of affected individuals have mutations in this gene. Cases can be caused by inherited mutations or spontaneous mutation that occur randomly in families; therefore, there is an absence of a family history. Defects in the skin usually develop at birth in four distinct stages. The first stage usually occurs before four

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months old when the blisters appear in the skin. The second stage involves a wart-like rash that eventually turns into the third stage, in which regions of swirling, darkened pigmentation (skin color) appear after six month of age (and into adulthood). The last stage is characterized by linear hypopigmentation, or areas of the body that are less darkly pigmented.

Other symptoms include defects in the teeth, with too few or too many present. The finger and toenails can often be brittle or pitted, often resembling fungal infections. Patients often have alopecia (hair loss) that occurs on the scalp or body trunk and extremities. Hair can appear patchy and hair loss can occur in areas that blistered during the first stage of the disease. Some patients have been reported to have defects in blood flow in the retina of the eye, predisposing them to retinal detachment during childhood.

Diagnosis Diagnosis is achieved first by a clinical diagnosis from a clinical geneticist, followed by molecular genetic testing in a CLIA-approved diagnostic laboratory. This test usually supports DNA sequencing of the IKBKG gene. A mutation in this gene can confirm the clinical diagnosis. The clinical diagnosis requires the presence of involved skin that displays any or all the following symptoms, including blisters anywhere on the body except the face, usually before four months of age, hyperpigmentation (increased areas of pigment) occurring on the trunk of the body that fades during adolescence, and/or hairless streaks or patches that occur after adolescence.

Treatment team The treatment team consists of a neurologist, clinical geneticist, genetic counselor, speech pathologist, ophthalmologist, and a dermatologist. A specialist that deals with learning disorders or developmentally delayed children may be necessary in certain cases.

Treatment As there is no cure for incontinentia pigmenti, treatment is based on symptoms. The risk of infection from blisters is a consideration, and topical medications can often be used to lessen the associated pain. Corrective dentistry might be necessary to help with eating and talking.

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Key Terms Cognitive delay Impairment or slowing of the mental processes of thinking and acquiring knowledge. Dominant disorder A disorder resulting from an inheritance pattern where one parent has a single, faulty dominant gene, and has a 50% chance of passing on that faulty gene to offspring with each pregnancy. Hyperpigmentation An excess of melanin, leading to abnormal areas of increased dark skin color.

“Incontinentia Pigmenti.” Incontinentia Pigmenti International Foundation (IPIF). April 23, 2004 (June 2, 2004). . “NINDS Incontinentia Pigmenti Information Page.” National Institute of Neurological Disorders and Stroke. April 23, 2004 (June 2, 2004). . ORGANIZATIONS

Incontinentia Pigmenti International Foundation (IPIF). 30 East 72nd Street, 16th Floor, New York, NY 10021. (212) 452-1231; Fax: (212)452-1406. [email protected]. .

Hypopigmentation A deficiency of melanin, leading to abnormal areas of lighter skin color. Neurocutaneous Conditions involving unique manifestations of the skin, hair, teeth, and nervous system, usually with familial tendencies.

Bryan Richard Cobb, PhD

Infantile hypotonia see Hypotonia Infantile phytanic acid storage disease see Refsum disease

Recovery and rehabilitation There is no cure for incontinentia pigmenti. A speech pathologist and a nutritionist can often help with rehabilitation to address problems associated with speech difficulties and difficulties eating.

Infantile Refsum disease see Refsum disease

❙ Infantile spasms

Clinical trials As of mid-2004, there were no ongoing clinical trials specific for the study or treatment of incontinentia pigmenti.

Prognosis The skin abnormalities can improve with age and in some instances disappear completely. The prognosis for neurological abnormalities depends on each case, but is often permanent and significant. Life expectancy, however, is considered normal.

Special concerns Genetic counseling is important in cases in which there is a family history of incontinentia pigmenti, or in which there is a clinical diagnosis. Resources BOOKS

Staff. The Official Parent’s Sourcebook on Incontinentia Pigmenti: A Revised and Updated Directory for the Internet Age. San Diego: Icon Group International, 2002.

Definition

Infantile spasms (IS) are seizures seen in epilepsy of infancy and early childhood. The typical pattern of an infantile spasm occurs soon after arousal from sleep, and involves a sudden bending forward and stiffening of the body, arms, and legs. Additionally, arching of the torso can also be seen during an infantile spasm. Infantile spasms typically last for one to five seconds and occur in clusters, ranging from two to 100 spasms at a time.

Description Infantile spasms were first described by the English physician W.J. West (1794–1848) in 1841. West’s paper, published in the first volume of the medical journal Lancet, was a landmark in the development of pediatric neurology, and the seizure syndrome also became known as West syndrome. West observed the condition in his own infant son, giving a precise and complete description of the symptoms, along with the gradual mental deterioration, and intractability of the syndrome. Other neurological disorders, such as cerebral palsy, may be seen in almost half of infants with infantile spasms.

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OTHER

Infantile spasms

Incontinentia Pigmenti, Type II

male

male

stillborn

male

See Symbol Guide for Pedigree Charts. (Gale Group.)

Infantile spasms may have variable features, but have been categorized primarily into three subtypes based on manifestations of posture and patterns of muscle involvement during the seizure. Flexor spasms involve flexion of the neck, trunk, and extremities. Extensor spasms consist of extension of the neck, trunk, and extremities. Mixed flexor-extensor spasms involve combinations of the above. In many patients, spasms exhibit characteristic patterns involving time. Fifty to eighty percent of the epileptic spasms occur in clusters of two to more than 100 seizures. Patients may have dozens of clusters and several hundred spasms per day, but individual variability in seizure frequency is often large. Although spasms rarely occur during sleep, clusters of spasms are frequently activated after awakening from sleep. Spasms are occasionally triggered by loud noises with associated arousal from drowsiness and sleep, but are generally not sensitive to stimulation by human voices.

Demographics In the United States, infantile spasms constitute 2% of childhood epilepsies, and 25% of epilepsies with onset in the first year of life. The rate of IS is 1.6–5.0 cases per 10,000 live births. As many as 5% of infants with this condition eventually die from complications of the seizures. Although males are affected slightly more often than females, no significant gender difference is noted.

Causes and Symptoms The number of neurological diseases that can result in infantile spasms is very large, but some of the major categories include intrauterine injury and infection, disorders caused by lack of blood flow to the fetal brain, developmental malformations of the cerebral cortex, metabolic 452

Key Terms Electroencephalogram (EEG) A procedure that uses electrodes on the scalp to record electrical activity of the brain. Used for detection of epilepsy, coma, and brain death. Epilepsy Disorder associated with the disturbed electrical discharges in the central nervous system that cause seizures. Seizure Abnormal electrical discharge of brain tissue, often resulting in abnormal body movements or behaviors.

disorders, other genetic or chromosomal defects, meningitis, and tumors. These seizures are assumed to reflect abnormal interactions between the cortex and brainstem structures. The frequent onset of the spasms in infancy suggests that an immature central nervous system may be important in the formation of infantile spasm syndrome. One theory states that the effect of different stressors in the immature brain produces an abnormal excessive secretion of corticotropin-releasing hormone, which causes spasms. In 90% of children with the condition, infantile spasms occur in the first year of life, typically between three to six months of age. Often, in the beginning, the attacks are brief, infrequent and not typical, so it is quite common for the diagnosis to be delayed. Frequently, because of the pattern of attacks and the cry that a child gives during or after an attack, they are initially thought to be due to colic, or gastric distress.

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Typically, each episode lasts a few seconds, followed by a pause of a few seconds, and a further spasm. While single spasms may occur, infantile spasms usually occur in sets of several spasms in a row. It is common for babies with infantile spasms to become irritable and for their development to slow down or even regress until the spasms are controlled.

Diagnosis Information about the child’s seizures and about the pregnancy, birth, and progress since birth, will help the physician in making the diagnosis. The diagnosis of infantile spasms is made by a combination of the typical features, along with a characteristic electroencephalogram (EEG), which shows a very disorganized pattern termed hypsarrhythmia. Most children with infantile spasms will need a number of tests, such as blood, urine, and cerebrospinal fluid (fluid which circulates around the brain and spinal cord) sampling, in an attempt to screen for any infection or metabolic abnormality. X-ray studies such as CT scans, ultrasound, or MRI will be performed to evaluate the structure of the brain.

Treatment Team The treatment team usually includes pediatric neurologists, neurosurgeons, nurses specializing in epilepsy care, and dietitians. In addition to conventional therapies, the team provides the latest in diagnostic and therapeutic approaches, including such innovations as the ketogenic diet, diagnostic video telemetry, and epilepsy surgery for intractable seizures. New epilepsy studies focus in investigating promising new drugs and other novel therapies.

Treatment Due to the poor prognosis of infantile spasms, treatment is usually initiated quickly and aggressively after diagnosis, often at the risk of serious side effects, with the hope of changing the natural history of the disease. Antiepileptic medications are the mainstay of therapy for infants with infantile spasms. Unfortunately, no one medical treatment gives satisfactory relief for all patients. In most open-label or retrospective studies, adrenocorticotrophic hormone ACTH or prednisone induces a reduction or complete cessation of spasms, as well as an

improvement in the EEG, in approximately 50–75% of patients. This effect is usually achieved within a couple weeks. Patients unresponsive to ACTH may respond to prednisone and vice-versa. A large variety of ACTH doses have been used, but there is no evidence that larger doses (150 units/day) are more effective than lower doses (20–30 units/day). While relapses occur in about one-third to onehalf of patients, a second course of ACTH is often effective. Among conventional anti-seizure drugs, valproate and nitrazepam have been shown to be effective as first-line therapy. In addition to medication, there are some potential surgical options for infantile spasms, although they may only be applicable to a small percentage of patients. Although in most patients the precise source of the spasms in the brain cannot be localized, there is a small minority of patients who have secondarily generalized spasms from lesions in the brain that can be surgically removed. Newer anti-seizure medicines such as Vigabatrin, although not yet approved in the United States, have shown promise in reducing the frequency of infantile spasms by increasing the brain’s available amount of GABA, a neurotransmitter that helps transmit information as it bridges the gaps between nerve cells.

Recovery and rehabilitation Infantile spasms usually cease spontaneously by age five, but are often replaced by seizures of other types. Therefore, emphasis is placed on lifelong seizure prevention rather than recovery. Maintaining control of seizures in infancy can sometimes reduce developmental delays and mental retardation, although most infants will already have significant neurological impairment before the onset of symptoms.

Clinical trials Although as of early 2004, there were no ongoing clinical trials for infantile spasms, the National Institutes of Health (NIH) sponsors research related to many seizure disorders. Information on the numerous current clinical trials for the study and treatment of seizure disorders can be found at the NIH website: .

Prognosis Infantile spasms usually resolve with or without treatment in the majority of patients, generally by mid-childhood. However, other seizure types arise in 50–70% of patients. Similarly, on long-term follow-up, chronic intractable (unable to respond to treatment) epilepsy is present in approximately 50% of patients with a history of infantile spasms.

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The typical pattern is of a sudden flexion (bending forward) in a tonic (stiffening) fashion of the body, arms, and legs. Sometimes, however, the episodes are of the extensor type (arching). Usually, they are symmetrical, but sometimes one side is affected more than the other.

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Mental retardation occurs in 70–90% of persons with infantile spasms, usually involving severe to profound retardation. Other neurological deficits, such as cerebral palsy, may be seen in about 30–50% of patients. By far, the most important factor in predicting neurological prognosis, including developmental outcome and long-term epilepsy, is the underlying cause of the seizures. Factors that have been associated with a good prognosis include normal neurological exam and development at onset, absence of other seizure types at onset, older age of onset, short duration of spasms, and early effective treatment of spasms (reported with ACTH).

Special concerns Once infants begin to have infantile spasms, they often fail to meet new milestones and may even regress, losing mental or physical skills previously learned. When the seizures begin, parents may notice a loss of interest in people and objects in the child’s environment. Social interaction may diminish, smiling may cease, sleep may become disrupted, and the child may seem irritable or indifferent to surroundings. A child who had learned to sit may stop sitting or even lose the ability to roll over; a child who had been babbling happily may become silent or fussy. Resources BOOKS

Frost, James D., Jr., and Richard A. Hrachovy. Infantile Spasms: Diagnosis, Management and Prognosis. New York: Kluwer Academic Publishers, 2003. PERIODICALS

Shields, W. D. “West’s syndrome.” J. Child Neurol 17 (2002): S76–79. West, W. J. “On a peculiar form of infantile convulsions.” Lancet (1840–1841) I: 724–725. OTHER

National Institute of Neurological Disorders and Stroke. NINDS Infantile Spasms Information Page. (April 5, 2004). . ORGANIZATIONS

Epilepsy Foundation. 4351 Garden City Drive, Landover, MD 20785-7223. (301) 459-3700 or (800) 332-1000. (301) 577-2684. [email protected]. . National Organization for Rare Disorders (NORD). 55 Kenosia Avenue, Danbury, CT 06813-1968. (203) 744-0100; Fax: (203) 798-2291. [email protected]. .

Francisco de Paula Careta Iuri Drumond Louro 454

❙ Inflammatory myopathy Definition

Inflammatory myopathy is a term that defines a group of muscle diseases involving inflammation and degeneration of skeletal muscle tissues. They are thought to be autoimmune disorders. In inflammatory myopathies, inflammatory cells surround, invade, and destroy normal muscle fibers as though they were defective or foreign to the body. This eventually results in discernible muscle weakness. This muscle weakness is usually symmetrical and develops slowly over weeks to months or even years. When using the term inflammatory myopathy, one is actually considering three separate disease entities, namely dermatomyositis (DM), polymyositis (PM), and inclusion body myositis (IBM). Although all of these diseases result in muscle weakness, each is unique in its development and treatment.

Description Inflammatory myopathies include a diverse group of disorders ranging from localized varieties confined to a single muscle or group of muscles, to diffuse forms in which there is widespread involvement of the skeletal muscles. Inclusion body myositis (IBM) mainly affects individuals over the age of 50. The onset is truly insidious with symptoms often having been present for more than five years before diagnosis. Clinically and histologically, IBM may appear identical to another inflammatory myositis called polymyositis, although differences are clear in more than half the patients. Weakness in (IBM) may be localized in the extremities, or asymmetric, and it may be accompanied by diminished deep-tendon reflexes. Disease progression is usually slow and steady in some, while it seems to plateau in others, leaving them with fixed weakness and atrophy (muscle wasting) of the involved musculature. In the muscle tissue, a characteristic change in IBM is the presence of intracellular rimmed vacuoles (pockets). The muscle fibers with pockets are now recognized to contain abnormal deposits of amyloid proteins. Polymyositis usually occurs after the second decade of life and is a subacute myopathy (one that occurs over time) that evolves over weeks or months, and presents with weakness of the arm and leg muscles. PM mimics many other myopathies. It should be viewed as a syndrome of diverse causes that occurs separately or in association with other autoimmune disorders. In PM, muscle fibers are found to be in varying stages of necrosis (tissue death) and regeneration.

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Amyloid A waxy, translucent, starch-like protein that is deposited in tissues during the course of certain chronic diseases such as rheumatoid arthritis and Alzheimer’s disease. Autoimmune Pertaining to an immune response by the body against its own tissues or types of cells.

Dermatomyositis (DM) is identified by a characteristic skin rash accompanying or, more commonly, preceding muscle weakness. DM affects children and adults and presents a varying degree of muscle weakness that develops slowly, over weeks to months.

Demographics In the United States and Canada, IBM accounts for approximately 15–28% of all cases of inflammatory myopathies. IBM most frequently affects men with a male to female ratio of 3:1. No race predilection for IBM is known, but it is uncommon among African-Americans and has been reported in Europe and Asia. Assessing demographic data is difficult due to the fact that IBM patients often exhibit other medical problems. Polymyositis (PM) is most common among black people and is most prevalent in women, with a male to female ratio of 1:2. In the United States, its incidence is one per 100,000 persons per year. Dermatomyositis (DM) affects mainly white people and is more prevalent in women, with a male to female ratio of 1:2. In the United States, the estimated incidence is 5.5 cases of DM per one million people.

Causes and symptoms Inclusion body myositis (IBM) is thought to be a sporadic disease, meaning one that is not hereditary. The cause of IBM remains unknown, but is thought to be a form of autoimmune disease, where the immune system responds in a harmful manner to the rest of the body. Very rarely, IBM can be present within families, and it is not known whether this form is inherited or if family members have another susceptibility to whatever causes the sporadic form of the disease. The trigger mechanism for all inflammatory myopathies remains unknown. Some scientists maintain that a viral illness causes an injury that activates a flawed immune response. Other scientists, noting that cancer sometimes occurs along side some types of inflammatory myopathy, are investigating the relationship between the

Weakness of muscle function in the area affected is usually the first symptom of inflammatory myopathy. The distribution of weakness is variable, and involvement of the knee extensor muscle and the wrist and finger flexor muscles are common. Fatigue is common, along with reduced tolerance to exertion, difficulty swallowing (dysphagia), and some forms of heart disease. In polymyositis (PM), weakness and muscle pain on both sides of the body at rest or with use are the first signs of the disease. The weakness becomes chronic, lasting for weeks or months. If swallowing muscles are involved, dysphagia may occur. Joint pain and difficulty kneeling, climbing, or descending stairs, raising arms, and arising from a sitting or lying position are also noticeable. People often present with skin disease as one of the initial manifestations of DM. A characteristic rash preceding or accompanying muscle weakness, or a confluent, purple-red rash with swelling in surrounding tissues appears. Other rashes seen with DM include swelling at the nail beds and a scaly purple eruption over the knuckles. Muscle involvement varies from mild to severe. The muscle wall of the heart or lung tissues may also become inflamed as a consequence of DM. Some cancers have been associated with DM, a finding much more common in adults over 60 years old.

Diagnosis A muscle biopsy provides a definitive diagnosis for inflammatory myopathies. Muscle biopsy is also important for the exclusion of other neuromuscular diseases. Blood levels of creatine kinase, an enzyme present in the brain and skeletal and cardiac muscles, are usually elevated in persons with muscle damage, and are useful in the diagnosis of inflammatory myopathies. According to The Myositis Association, the main clinical features for diagnosis of inclusion body myositis (IBM) are: • Duration of illness greater than six months • Age of onset greater than 30 years old • Muscle weakness that affects the arms and legs • At least one of the following: weakness when flexing the fingers, differing degrees of weakness when flexing and extending the wrist, and weakness in the quadriceps muscle of the thigh. In polymyositis (PM), the presence of inflammation in muscle tissue is hallmark of the disease. The diagnosis

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Key Terms

two diseases. A genetic predisposition may exist for DM, and abnormal activities of certain white blood cells may be involved in the cause of both the skin and the muscle disease.

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of PM is made when a person has continued elevated levels of serum creatine kinase and characteristic findings on muscle biopsy. Polymyositis is difficult to diagnose due to its ability to mimic other chronic diseases. People with dermatomyositis (DM) often have characteristic rashes that accompany chronic weakness, making the tentative diagnosis easier for the physician and patient. Skin lesions can include red, raised areas on the surface of the joints of the arms and legs, face, or upper body.

Treatment team A neurologist or rheumatologist is the primary consultant for both IBM and PM, with allied health care areas including but not limited to physical therapists and otolaryngology.

Treatment Currently, no treatment has been shown to be effective against the different forms of IBM. Some moderate success has been obtained with the combination of corticosteroids and methotrexate or human intravenous immunoglobulins (IVIg). New therapeutic protocols are currently being tested. In PM, however, high-dose corticosteroid therapy constitutes the first-line of treatment, and leads to improvement in more than 70% of persons with PM. Different therapeutic alternatives can be attempted with immunosuppressants, notably azathioprine, methotrexate and intravenous immunoglobulins (IVIg). The same approach is useful for DM.

and Musculoskeletal and Skin Diseases (NIAMS) is examining whether the drug infliximab (Remicade) is safe for treatment of DM and PM. Information about all current clinical trials can be found at the U.S government website for clinical trials: http://www.clinicaltrials.org.

Prognosis IBM generally worsens progressively and slowly. Sometimes the condition stabilizes spontaneously or while the person is under treatment, but periods are usually transient and the inflammation reoccurs. Before the era of corticosteroids, PM and DM were particularly severe diseases with spontaneous survival rates of less than 40%. Currently, in the absence of an underlying disease such as cancer, PM and DM in adults have a relatively favorable prognosis, with a five-year survival rate of around 90%. For children, the vascular damage of DM can be responsible for severe complications, such as perforations or hemorrhages.

Special concerns Exercise is generally helpful to retain movement, and helps to get the most out of diseased muscles. Falls and injuries, however, can cause substantial disability for a person with an inflammatory myopathy. It is important, therefore, to maintain regular exercise within a safe capacity and avoid injury. Because weakened muscles cannot carry an excess load, keeping to an ideal weight is also helpful. A well-balanced diet is important and people with severe inflammation of the muscles may need extra protein. Resources BOOKS

Recovery and rehabilitation In most cases of inflammatory myopathies, there is continued deterioration, in spite of any reduction of muscle inflammation that treatments may provide. Because of the slow progression, any medication regimes often continue for at least six months (possibly 12-18 months) to gain the most benefit. Physical therapy and occupational therapy help with walking, limb range of motion and positioning if the person’s disability increases. About 30% of persons with PM achieve complete recovery, with the majority of patients having a persistent deficit in movement and strength.

Clinical trials The National Institute of Neurological Disorders and Stroke (NINDS) has sponsored a study entitled “Immune Abnormalities in Sporadic Inclusion Body Myositis.” This is an investigative study intended to better define the pathogenesis of IBM. The National Institute of Arthritis 456

Kilpatrick, James R., compiler. Coping with a Myositis Disease. Birmingham, AL: AKPE, 2000. PERIODICALS

Mastaglia, F. L., M. J. Garllep, B. A. Phillips, and P. J. Zilko. “Inflammatory myopathies: clinical, diagnostic and therapeutic aspects.” Muscle & Nerve (April/2003): 407–425. OTHER

“NINDS Inclusion Body Myositis Information Page.” National Institute of Neurological Disorders and Stroke. (February 11, 2004). . ORGANIZATIONS

Muscular Dystrophy Association. 3300 E. Sunrise Drive, Tucson, AZ 85718,. (800) 572-1717. [email protected]. . Myositis Association of America. 755 Cantrell Ave., Suite C, Harrisonburg, VA 22801. (540) 433-7686; Fax: (540) 4320206. [email protected]. .

Marcos do Carmo Oyama Iuri Drumond Louro

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Definition

Interferons are a group of proteins called cytokines produced by white blood cells, fibroblasts, or T-cells as part of an immune response to a viral infection or other immune trigger. The name of the proteins comes from their ability to interfere with the production of new virus particles.

Purpose Interferons affect the immune system in a number of ways. For example, interferon beta can enhance the activity of lymphocyte cells while simultaneously inhibiting other immune cells from becoming stimulated. Additionally, interferon beta regulates the production of interferon gamma. Interferons can also inhibit viruses from establishing an infection inside human cells. Interferon alfa displays anti-tumor activity. The exact molecular details of how interferons act is still unclear. They may make surface-exposed antigens of tumors even more capable of stimulating the immune system, which in turn would elicit a greater response from the T-cells of the immune system. Tumor growth may also be slowed or retarded by interferon-mediated damage to the blood cells that supply the tumor with nourishment.

Description There are three types of interferons: alfa, beta, and gamma. Alfa and beta interferons, which are grouped together as type I interferon, are produced by white blood cells and a type of connective tissue cell called a fibroblast. Gamma interferon (or type II interferon) is manufactured T-cells. Production occurs when the T-cells are activated such as during an infection. The alfa and beta interferons share some biological activities, but also have activities that are distinct from one another. These similarities and differences reflect the common and different binding of the interferons to various targets (receptors) on the surfaces of human cells. Alfa interferon is manufactured by Roche Products (trade name Pegasys) and Schering-Plough (ViraferonPeg). Biogen (Avonex) and Serono (Rebif) both market an interferon-designated beta-1a. Both of the beta-1a interferons are produced in genetically engineered mammals. For example, Rebif is produced in Chinese hamster ovary cells that contain the gene coding for human interferon beta. An interferon designated as beta-1b enhances the activity of T-cells, while simultaneously reducing the production cytokines that operate in the inflammatory

Key Terms Demyelinating diseases A group of diseases characterized by the breakdown of myelin, the fatty sheath surrounding and insulating nerve fibers. This breakdown interferes with nerve function, and can result in paralysis. Multiple sclerosis is a demyelinating disorder. Interferon alfa A potent immune-defense protein that is used as an anti-cancer drug.

response to infection and injury. As well, this interferon retards the exposure of antigens on the surface of cells (and so lessens the development of an immune response to the antigens), and retards the appearance of white blood cells (lymphocytes) in the central nervous system. The reduction of the immune response can lessen the damage to nerve cells in diseases such as multiple sclerosis. In this disease, the immune system is stimulated to react against the myelin sheath that surrounds the cells, a phenomenon called demyelination. Demyelination produces a malfunction in the transmission of impulses from nerve to nerve and from nerve to muscle. Infection with the virus that causes hepatitis C is hindered by interferon via the binding to a site on human cells that is also used by the virus. Thus, the virus cannot enter and infect the host cell. In the late 1980s, a large clinical trial conducted in the United States and Canada evaluated the influence of interferon beta-1b (Betaseron, marketed by Berlex) made in bacteria using genetic engineering technology. Specifically, the bacterium Escherichia coli contained a piece of genetic material (plasmid) that contains the gene coding for human beta interferon. The study was double-blind (neither the test participants or the researchers knew which person was receiving the real drug or a placebo). The twoyear study demonstrated that those people receiving the interferon had fewer reappearances of the symptoms, and fewer nerves in the brain were damaged. Betaseron was approved in 1993 by the U.S. Food and Drug Administration for use by people affected with multiple sclerosis. Avonex was approved in 1996 and Rebif in 2002.

Recommended dosage Interferons are normally injected. They are not taken by mouth as the strong digestive enzymes of the stomach will degrade them.

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❙ Interferons

Interferons

For use in multiple sclerosis, interferon beta-1a is injected into the muscle (intramuscular injection), and beta1b is injected just below the skin (subcutaneous injection). The injections are usually given every other day. The recommended dose for beta-1a and 1b is 0.03 mg and 0.25 mg, respectively. Initial doses of beta-1b should be far less (i.e., 0.0625 mg), with a gradual increase in dose over six weeks.

Precautions Patients who have had seizures or who are at risk for a seizure should be closely monitored following the injection of interferon, as should those with heart disorders such as angina, congestive heart failure, or an irregular heartbeat. It is not known if interferon can be expressed in breast milk. Concerned mothers may opt to cease breast-feeding while receiving interferon therapy.

Side effects Interferon beta 1-a and 1-b commonly produce flulike symptoms, including fever, chills, sweating, muscle aches, and tiredness. These side effects tend to diminish with time. Menstrual cycle changes have also been documented in a significant number of women. Far less commonly, interferon beta 1-a and 1-b can produce suicidal feelings in someone who is already clinically depressed. Death of cells around an injection site (necrosis) can occur, as can swelling and bruising. Allergic reactions are possible. The massive and sometimes fatal allergic reaction termed anaphylaxis occurs rarely. Other side effects include liver and thyroid malfunction, and altered blood chemistry (fewer platelets and red and white blood cells).

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Interactions As of December 2003, drug interaction studies have not been conducted. Resources BOOKS

Lotze, M. T., R. M. Dallal, J. M. Kirkwood, and J. C. Flickinger. “Cutaneous Melanoma.” In Principles and Practice of Oncology, edited by V. T. DeVita, S. A. Rosenberg, and S. Hellmon. Philadelphia: Lippincott, 2001. PERIODICALS

Aguilar, R. F. “Interferons in Neurology.” Rev Invest Clin 52, no. 6 (2000): 665–679. Polman, C. H., and B. M. J. Uitdehaag. “Drug Treatment of Multiple Sclerosis.” BMJ 321 (2000): 490–494. OTHER

National Multiple Sclerosis Society. Interferons. National Multiple Sclerosis Society Sourcebook. December 28, 2003. (May 22, 2004). . ORGANIZATIONS

National Multiple Sclerosis Society. 733 Third Avenue, New York, NY 10017. (800) 344-4867. .

Brian Douglas Hoyle, PhD

Intestinal lipodystrophy see Whipple’s disease Intracranial cysts see Arachnoid cysts

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J ❙ Joubert syndrome Definition

Joubert syndrome is a well-documented but rare autosomal recessive disorder. The syndrome is characterized by partial or complete absence of the cerebellar vermis (the connective tissue between the two brain hemispheres), causing irregular breathing and severe muscle weakness. Other features of the syndrome include jerky eye movements, abnormal balance and walking, and mental handicap. Additionally, there may be minor birth defects of the face, hands, and feet.

Description Marie Joubert (whose name is given to the condition) gave a detailed description of the syndrome in 1969. She wrote about four siblings (three brothers, one sister) in one family with abnormal breathing, jerky eye movements (nystagmus), poor mental development, and ataxia (staggering gait and imbalance). X-ray examination showed that a particular section of the brain, called the cerebellar vermis, was absent or not fully formed. This specific brain defect was confirmed on autopsy in one of these individuals. Her initial report also described a sporadic (non-inherited) patient with similar findings, in addition to polydactyly. Another name for Joubert syndrome is Joubert-Bolthauser syndrome.

Demographics Joubert syndrome affects both males and females, although more males (ratio of 2:1) have been reported with the condition. The reason why more males have the condition remains unknown. Joubert syndrome is found worldwide, with reports of individuals of French Canadian, Swedish, German, Swiss, Spanish, Dutch, Italian, Indian, Belgian, Laotian, Moroccan, Algerian, Turkish, Japanese, and Portuguese origin. In all, more than 200 individuals have been described with Joubert syndrome.

Causes and symptoms Although the underlying genetic cause remains unknown, there have been numerous instances of siblings (brothers and sisters) with Joubert syndrome. The parents were normal. A few families have also been seen where the parents were said to be closely related (i.e., may have shared the same altered gene within the family). For these reasons, Joubert syndrome is classified as an autosomal recessive disorder. Autosomal means that both males and females can have the condition. Recessive means that both parents carry a single copy of the responsible gene. Autosomal recessive disorders occur when a person inherits a particular pair of genes that do not work correctly. The chance that this would happen to children of carrier parents is 25% (one in four) for each pregnancy. It is known that the cerebellum and brain stem begin to form between the sixth and twelfth week of pregnancy. The birth defects seen in Joubert syndrome must occur during this crucial period of development. The cerebellum is the second largest part of the brain. It is located just below the cerebrum, and is partially covered by it. The cerebellum consists of two hemispheres separated by a central section called the vermis. The cerebellum is connected to the spinal cord through the brain stem. The cerebellum (and vermis) normally works to monitor and control movement of the limbs, trunk, head, and eyes. Signals are constantly received from the eyes, ears, muscles, joints, and tendons. Using these signals, the cerebellum is able to compare what movement is actually happening in the body with what is intended to happen, then send an appropriate signal back. The effect is to either increase or decrease the function of different muscle groups, making movement both accurate and smooth. In Joubert syndrome, the cerebellar vermis is either absent or incompletely formed. The brain stem is sometimes quite small. The absence or abnormal function of

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KEY TERMS Apnea An irregular breathing pattern characterized by abnormally long periods of the complete cessation of breathing. Ataxia A deficiency of muscular coordination, especially when voluntary movements are attempted, such as grasping or walking. Cerebellum A portion of the brain consisting of two cerebellar hemispheres connected by a narrow vermis. The cerebellum is involved in control of skeletal muscles and plays an important role in the coordination of voluntary muscle movement. It interrelates with other areas of the brain to facilitate a variety of movements, including maintaining proper posture and balance, walking, running, and fine motor skills, such as writing, dressing, and eating. Iris The colored part of the eye, containing pigment and muscle cells that contract and dilate the pupil. Nystagmus Involuntary, rhythmic movement of the eye. Polydactyly The presence of extra fingers or toes. Retina The light-sensitive layer of tissue in the back of the eye that receives and transmits visual signals to the brain through the optic nerve. Vermis The central portion of the cerebellum, which divides the two hemispheres. It functions to monitor and control movement of the limbs, trunk, head, and eyes.

these brain tissues causes problems in breathing and vision, and severe delays in development. One characteristic feature of Joubert syndrome is the pattern of irregular breathing. The individuals’s breathing alternates between deep rapid breathing (almost like panting) and periods of severe apnea (loss of breathing). This is usually noticeable at birth. The rate of respiration may increase more than three times that of normal (up to 200 breaths per minute) and the apnea may last up to 90 seconds. The rapid breathing occurs most often when the infant is awake, especially when they are aroused or excited. The apnea happens when the infants are awake or asleep. Such abnormal breathing can cause sudden death or coma, and requires that these infants be under intensive care. For unknown reasons, the breathing tends to improve with age, usually within the first year of life. Muscle movement of the eye is also affected in Joubert syndrome. It is common for the eyes to have a quick, 460

jerky motion of the pupil, known as nystagmus. The retina (the tissue in the back of the eye that receives and transmits visual signals to the brain) may be abnormal. Some individuals (most often the males) may have a split in the tissue in the iris of the eye. Each of these problems will affect their vision, and eye surgery may not be beneficial. The central nervous system problem affects the larger muscles of the body as well, such as those for the arms and legs. Many of the infants will have severe muscle weakness and delays in development. They reach normal developmental milestones, such as sitting or walking, much later than normal. For example, some may learn to sit without support around 19–20 months of age (normal is six to eight months). Most individuals are not able to take their first steps until age four or older. Their balance and coordination are also affected, which makes walking difficult. Many will have an unsteady gait, and find it difficult to climb stairs or run, even as they get older. Cognitive (mental) delays are also a part of the syndrome, although this can be variable. Most individuals with Joubert syndrome will have fairly significant learning impairment. Some individuals will have little or no speech. Others are able to learn words, and can talk with the aid of speech therapy. They do tend to have pleasant and sociable personalities, but problems in behavior can occur. These problems most often are in temperament, hyperactivity, and aggressiveness. Careful examination of the face, especially in infancy, shows a characteristic appearance. They tend to have a large head, and a prominent forehead. The eyebrows look high, and rounded, and the upper eyelids may be droopy (ptosis). The mouth many times remains open, and looks oval shaped in appearance. The tongue may protrude out of the mouth, and rest on the lower lip. The tongue may also quiver slightly. These are all signs of the underlying brain abnormality and muscle weakness. Occasionally, the ears look low-set on the face. As they get older, the features of the face become less noticeable. Less common features of the syndrome include minor birth defects of the hands and feet. Some individuals with Joubert syndrome have extra fingers on each hand. The extra finger is usually on the pinky finger side (polydactyly). It may or may not include bone, and could just be a skin tag. A few of these patients will also have extra toes on their feet.

Diagnosis The diagnosis of Joubert syndrome is made on the following features. First, there must be evidence of the cerebellar vermis either being absent or incompletely formed. This can be seen with a CT scan or MRI of the brain. Second, the physician should recognize that the in-

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Treatment During the first year of life, many of these infants require a respiratory monitor for the irregular breathing. For the physical and mental delays, it becomes necessary to provide special assistance and anticipatory guidance. Speech, physical, and occupational therapy are needed throughout life.

Prognosis

This child is diagnosed with Joubert syndrome. Common symptoms of this disorder include mental retardation, poor coordination, pendular eye movement, and abnormal breathing patterns. (Photo Researchers, Inc.)

fant has both muscle weakness and delays in development. In addition, there may be irregular breathing and abnormal eye movements. Having four of these five criteria is enough to make the diagnosis of Joubert syndrome. Most individuals are diagnosed by one to three years of age.

Treatment team

The unusual pattern of breathing as newborns, especially the episodes of apnea, can lead to sudden death or coma. A number of individuals with Joubert syndrome have died in the first three years of life. For most individuals, the irregular breathing becomes more normal after the first year. However, many continue to have apnea, and require medical care throughout their life. Although the true life span remains unknown, there are some individuals with Joubert syndrome who are in their 30s. Resources ORGANIZATIONS

Joubert Syndrome Foundation Corporation. c/o Stephanie Frazer, 384 Devon Drive, Mandeville, LA 70448. OTHER

Alliance of Genetic Support Groups. . Joubert Syndrome Foundation Corporation. .

A pediatric neurologist usually sees children with Joubert syndrome. Physical, occupational, and speech and

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Kevin M. Sweet, MS, CGC Rosalyn Carson-DeWitt, MD

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language therapists are important members of the treatment team.

K ❙ Kennedy’s disease Definition

Kennedy’s disease is a rare genetic neurodegenerative disorder that affects the motor neurons (cells that are important for normal function of the brain and spinal cord). It is a progressive disorder that leads to increasing severity of motor dysfunction and subsequent deterioration of muscle strength, muscle tone, and motor coordination. It was first described by the American physician William R. Kennedy in 1966.

Description As Kennedy’s disease is a progressive neurodegenerative disorder, affected individuals have physical, mental, and emotional impacts. Physically, the neurological degenerative process results in muscle weakness and eventual muscle wasting that can affect the patient’s ability to walk or move. Kennedy’s disease is also called spinal bulbar muscular atrophy, or SBMA, because both the spinal and bulbar neurons are affected.

Demographics Kennedy’s Disease is inherited through the X chromosome, and since males only have one X chromosome inherited from their carrier mother, they are usually affected while females are usually carriers. Therefore, sons of carrier mothers will be affected and all her daughters have a 50% chance of being a carrier. Although affected males often have a low sperm count or are infertile, if they are capable of reproducing, all male children will be unaffected and all female children will be unaffected carriers. In some cases, women who are carriers also exhibit clinical symptoms, although they are generally less severe. Kennedy’s disease is a rare disease, with only one in 50,000 males affected and no particular pattern among various races or ethnic groups.

Causes and symptoms Symptoms do not usually develop until between the second and fourth decades of life, although an earlier (and a later) age of onset have been documented. Symptoms initially are mild and include tremors while stretching hands, muscle cramps after exertion, and fasciculations (visible muscle twitches). Muscle weakness often develops in the arms and legs, beginning usually in the shoulder or midsection. It is most noticeable in the legs and the arms. Breathing, swallowing, and talking are functions that require bulbar muscles controlled by motor nerves that communicate with the brain. The effects of bulbar muscle dysfunction can be manifested by slurred speech and dysphagia (swallowing difficulties). In later stages, patients often develop aspiration pneumonia (pneumonia caused by food and fluids traveling down the bronchial tubes instead of the trachea due to poor ability to swallow). Kennedy’s disease is caused by a trinucleotide repeat expansion in the androgen receptor gene. This means that three letters in the DNA alphabet (cytosine-adenine-guanine, or CAG) that are normally repeated 10–36 times expand to produce a larger repeat size of approximately a 40–62 repeated trinucleotide sequence. This sequence is unstable and can change from one generation to the next leading to further expansions. The specific mechanism explaining how this trinucleotide repeat expansion (which leads to an increased length in the protein it encodes) causes the disease is unknown.

Diagnosis Patients with Kennedy’s disease usually receive a definitive diagnosis in a clinical molecular genetics laboratory. This requires DNA extraction from blood, followed by testing the gene that causes Kennedy’s disease for a mutation. Kennedy’s disease can be misdiagnosed as spinal muscular atrophy and Lou Gehrig’s disease due to similar symptoms displayed.

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psychosocial consideration and need to be addressed. Erectile dysfunction and/or testicular atrophy may also affect males.

Key Terms Dysphagia Difficulty swallowing.

Resources

Fasciculations Fine muscle tremors.

BOOKS

X-linked disorder A disorder resulting from a genetic mutation on the X chromosome. Usually, males, having only one X chromosome, are affected with X-linked disorders; females are usually carriers.

Treatment team The treatment team caring for a patient with Kennedy’s disease includes a neurologist, physical therapists, occupational therapists, gastroenterologists, and genetic counselors.

Treatment Although research efforts are underway, currently there is no treatment for Kennedy’s disease. Medical treatment is based on lessening the symptoms. Physical therapy is useful in reducing the side affects from the progressive muscle weakness.

Recovery and rehabilitation In the absence of a cure, patients usually do not recover and the symptoms progress during their lifetime. Lifestyle changes may become necessary, especially late in the disease. These changes, in more severe cases, can include (but are not limited to) help eating, wheelchair access at home, and help with using the restroom and changing clothes.

Prognosis Kennedy’s disease is a neurodegenerative disorder that is slow in its progression. It is likely that individuals will become wheelchair bound during the later stages of the disease. Although individuals will have certain difficulties in motor function and may have special needs, the lifespan of affected individuals is not thought to be shortened.

Special concerns Genetic counseling is important in this disorder since the presence of one affected offspring means that it is likely the disease gene was inherited and that there is a risk that there will be affected offspring in subsequent generations. The possibility of infertility due to low sperm count should also be discussed during the counseling, especially in cases that develop early. Also, gynecomastia (enlarged breasts) in males due to reduced virilization can also have 464

Cooper, D. N., M. Krawczak, and S. E. Antonarakis. “The Nature and Mechanisms of Human Gene Mutation.” In The Metabolic and Molecular Basis of Inherited Disease, 7th ed. Edited by C. R. Scriver, A. L. Beaudet, W. S. Sly, and D. Valle. NY: McGraw-Hill, 1995. Icon Group Publications. The Official Parent’s Sourcebook on Spinal Muscular Atrophy: A Revised and Updated Directory for the Internet Age. San Diego: Icon Group International, 2002. Panzarino, Connie. Me in the Mirror. Seal Press, 1994. OTHER

“NINDS Kennedy’s Disease Information Page.” National Institute of Neurological Disorders and Stroke. (April 24, 2004). . “What Is Kennedy Disease?” Kennedy Disease Association. (April 24, 2004). . ORGANIZATIONS

National Organization of Rare Disorders. PO Box 8923, New Fairfield, CT 06812-8925. (203) 746-6518 or (800) 9996673; Fax: (203) 746-6481. [email protected]. . Kennedy’s Disease Association. PO Box 2050, Simi Valley, CA 93062-2050. (805) 577-9591. tswaite@ pacbell.net. .

Bryan Richard Cobb, PhD

Kinsbourne syndrome see Opsoclonus myoclonus

❙ Klippel Feil syndrome Definition

Klippel Feil syndrome is a rare congenital (present at birth) disorder in which there is abnormal fusion of some of the cervical (neck) vertebrae.

Description People with Klippel Feil syndrome are often identified due to three major characteristics: a short neck, a low hairline, and restricted neck mobility due to the fused cervical vertebrae. Klippel Feil syndrome can occur as a lone defect, or in association with other abnormalities, including scoliosis (curved spine), spina bifida (a birth defect

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involving the spinal column and cord), cleft palate, and a variety of defects involving the ribs, urinary tract, kidneys, heart, muscles, brain, and skeleton. Facial defects and problems with hearing and breathing may also occur in Klippel Feil syndrome.

Chromosome 8 23 2 22

Klippel Feil syndrome has been organized into three basic types. In type I, all of the cervical and upper thoracic vertebrae are fused together into one block. In type II, one or two pairs of cervical vertebrae are fused together. In type III, there is lower thoracic or lumbar fusion as well as cervical fusion.

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Hereditary spherocytosis

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Demographics

Cohen syndrome

Although not a lot of data has been collected regarding how often Klippel Feil syndrome occurs, the information available suggests that the incidence of this condition ranges from about one in 42,400 births to about three in 700 births. Boys are slightly more likely than girls to have this condition (1.5:1).

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Klippel Feil syndrome

2 23 MYC: Burkitt lymphoma 24

LGS: Langer-Giedon syndrome

Causes and symptoms Klippel Feil syndrome is believed to occur during very early fetal development, when the cervical vertebrae do not segment normally. The exact mechanism that causes the defect is unkown.

Klippel Feil syndrome, on chromosome 8. (Gale Group.)

Although most cases of Klippel Feil syndrome occur spontaneously, there have been a few reports of Klippel Feil syndrome that showed a pattern of inheritance within a family. In some cases, maternal alcoholism and subsequent fetal alcohol syndrome seems to be associated with Klippel Feil syndrome.

should be done to uncover associated defects. For example, children diagnosed with Klippel Feil syndrome should have a thorough hearing screening performed, due to the high risk of associated hearing problems. The cardiovascular system and the kidneys and urinary tract may also require evaluation.

Many individuals with Klippel Feil syndrome have no symptoms. Individuals who have more minimal degrees of fusion can live completely normally and partake in all activities. They may never become aware that they have any abnormality at all. Individuals with more severe degrees of fusion will be obviously impaired in terms of their neck mobility. Some individuals will suffer from torticollis or wry neck, a condition in which the neck muscles pull the neck to one side. If the spinal cord is constricted by the abnormal vertebrae, neurological symptoms (weakness, numbness, tingling) may result. A full 30–40% of all individuals with Klippel Feil syndrome will have significant structural abnormalities of their urinary tract. These often lead to chronic kidney infections (pyelonephritis), and a high risk of kidney failure.

Treatment team The treatment team will depend on the degree of disability brought on by the vertebral defects, and the presence of any associated problems. In more mildly affected individuals, a pediatrician and orthopedic surgeon may collaborate to achieve a diagnosis. In more severely affected individuals, a neurologist or neurosurgeon may need to be involved as well. Depending on what other body systems are involved, a cardiologist, nephrologist, urologist, and orofacial surgeon may be consulted. An audiologist can consult about hearing issues. A physical therapist and occupational therapist can be very helpful in helping with issues of mobility and ability to tend to activities of daily living.

Diagnosis Diagnosis is usually established through a variety of imaging techniques, such as plain x-ray films of the neck and spine, CT scan, or MRI. Other diagnostic studies

Treatment More mildly affected individuals will require no treatment. Other individuals may need surgery to improve cervical stability, correct scoliosis, and improve any

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Key Terms Cervical Referring to the neck. Cervical vertebrae are the first seven bones of the spine. Cleft palate A birth defect in which the roof of the mouth (palate) has an abnormal opening (cleft). Congenital A condition that is present at birth. Lumbar Referring to the lower back. There are five lumbar vertebrae. Spina bifida A birth defect in which there is an abnormal opening of the spinal column. The disability caused by this opening depends on the degree of the opening, and whether there are associated abnormalities of the development of the spinal cord and nerves. Thoracic Referring to the area of the torso commonly called the chest. There are 12 thoracic vertebrae. Torticollis A condition in which the muscles of the neck are abnormally contracted, pulling the neck off to one side. Vertebrae The stacked bones of the spinal column. There are seven cervical vertebrae, twelve thoracic vertebrae, five lumbar vertebrae, five sacral vertebrae (normally fused into the sacrum in adults), and four coccygeal vertebrae (normally fused into the coccyx in adults).

constriction of the spinal cord. Depending on the degree of scoliosis, a brace may be helpful. Physical therapy can be very helpful in order to improve strength and mobility. Occupational therapy can help more severely restricted individuals learn how to best perform activities of daily living, despite the limitations of their condition.

Prognosis The prognosis is excellent for very mildly affected people with Klippel Feil syndrome. With careful medical attention, the prognosis can be good for more severely affected individuals as well. Resources

Glycogenoses, and Leukodystrophies.” In Textbook of Clinical Neurology, edited by Christopher G. Goetz. Philadelphia: W.B. Saunders Company, 2003. Warner, William C. “Pediatric Cervical Spine” In Campbell’s Operative Orthopedics, edited by S. Terry Canale. St. Louis: Mosby Company, 2003. WEBSITES

National Institute of Neurological Disorders and Stroke (NINDS). NINDS Klippel Feil Syndrome Information Page. May 6, 2003. .

Rosalyn Carson-DeWitt, MD

❙ Krabbe disease Definition

Krabbe disease is an inherited enzyme deficiency that leads to the loss of myelin, the substance that wraps nerve cells and speeds cell communication. Most affected individuals start to show symptoms before six months of age and have progressive loss of mental and motor function. Death occurs at an average age of 13 months. Other less common forms exist with onset in later childhood or adulthood.

Description Myelin insulates and protects the nerves in the central and peripheral nervous system. It is essential for efficient nerve cell communication (signals) and body functions such as walking, talking, coordination, and thinking. As nerves grow, myelin is constantly being built, broken down, recycled, and rebuilt. Enzymes break down, or metabolize, fats, carbohydrates, and proteins in the body including the components of myelin. Individuals with Krabbe disease are lacking the enzyme galactosylceramidase (GALC), which metabolizes a myelin fat component called galactosylceramide and its by-product, psychosine. Without GALC, these substances are not metabolized and accumulate in large globoid cells. For this reason, Krabbe disease is also called globoid cell leukodystrophy. Accumulation of galactosylceramide and psychosine is toxic and leads to the loss of myelinproducing cells and myelin itself. This results in impaired nerve function and the gradual loss of developmental skills such as walking and talking.

BOOKS

Thompson, George H. “The Neck.” In Nelson Textbook of Pediatrics, edited by Richard E. Behrman, et al. Philadelphia: W.B. Saunders Company, 2004. Maertens, Paul, and Paul Richard Dyken. “Storage Diseases: Neuronal Ceroid-Lipofuscinoses, Lipidoses, 466

Demographics Approximately one in every 100,000 infants born in the United States and Europe will develop Krabbe disease. A person with no family history of the condition has a one GALE ENCYCLOPEDIA OF NEUROLOGICAL DISORDERS

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Ten percent of individuals with Krabbe disease have juvenile or adult type. Children with juvenile type begin having symptoms between three and ten years of age. They gradually lose the ability to walk and think. They may also have paralysis and vision loss. Their symptoms usually progress slower than in the infantile type. Adult Krabbe disease has onset at any time after age 10. Symptoms are more general including weakness, difficulty walking, vision loss, and diminished mental abilities.

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may have trouble eating and may have seizures. Development regresses leading to loss of mental and muscle function. They also lose the ability to see and hear. In the end stages, these children usually cannot move, talk, or eat without a feeding tube.

PS1(AD3): Alzheimer’s disease

Diagnosis

Krabbe disease

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Krabbe disease, on chromosome 14. (Gale Group.)

in 150 chance of being a carrier. Krabbe disease occurs in all countries and ethnic groups but no cases have been reported in the Ashkenazi Jewish population. A Druze community in Northern Israel and two Moslem Arab villages near Jerusalem have an unusually high incidence of Krabbe disease. In these areas, about one person in every six is a carrier.

Causes and symptoms Krabbe disease is an autosomal recessive disorder. Affected individuals have two nonfunctional copies of the GALC gene. Parents of an affected child are healthy carriers and therefore have one normal GALC gene and one nonfunctional GALC gene. When both parents are carriers, each child has a 25% chance to inherit Krabbe disease, a 50% chance to be a carrier, and a 25% chance to have two normal GALC genes. The risk is the same for males and females. Brothers and sisters of an affected child with Krabbe disease have a 66% chance of being a carrier. The GALC gene is located on chromosome 14. Over 70 mutations (gene alterations) known to cause Krabbe disease have been identified. One specific GALC gene deletion accounts for 45% of disease-causing mutations in those with European ancestry and 35% of disease-causing mutations in those with Mexican ancestry. Ninety percent of individuals with Krabbe disease have the infantile type. These infants usually have normal development in the first few months of life. Before six months of age, they become irritable, stiff, and rigid. They

There are many tests that can be performed on an individual with symptoms of Krabbe disease. The most specific test is done by measuring the level of GALC enzyme activity in blood cells or skin cells. A person with Krabbe disease has GALC activity levels that are zero to 5% of the normal amount. Individuals with later onset Krabbe disease may have more variable GALC activity levels. This testing is done in specialized laboratories that have experience with this disease. The fluid of the brain and spinal cord (cerebrospinal fluid) can also be tested to measure the amount of protein. This fluid usually contains very little protein but the protein level is elevated in infantile Krabbe disease. Nerveconduction velocity tests can be performed to measure the speed at which the nerve cells transmit their signals. Individuals with Krabbe disease will have slowed nerve conduction. Brain imaging studies such as computed tomography (CT scan) and magnetic resonance imaging (MRI) are used to get pictures from inside the brain. These pictures will show loss of myelin in individuals with Krabbe disease. DNA testing for GALC mutations is not generally used to make a diagnosis in someone with symptoms but it can be performed after diagnosis. If an affected person has identifiable known mutations, other family members can be offered DNA testing to find out if they are carriers. This is helpful since the GALC enzyme test is not always accurate in identifying healthy carriers of Krabbe disease. If an unborn baby is at risk to inherit Krabbe disease, prenatal diagnosis is available. Fetal tissue can be obtained through chorionic villus sampling (CVS) or amniocentesis. Cells obtained from either procedure can be used to measure GALC enzyme activity levels. If both parents have identified known GALC gene mutations, DNA testing can also be performed on the fetal cells to determine if the fetus inherited one, two, or no GALC gene mutations.

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Chromosome 14

Kuru

However, these procedures are not always successful and research is being done in order to reduce complications.

Key Terms Globoid cells Large cells containing excess toxic metabolic “waste” of galactosylceramide and psychosine. Motor function The ability to produce body movement by complex interaction of the brain, nerves, and muscles. Mutation A permanent change in the genetic material that may alter a trait or characteristic of an individual, or manifest as disease, and can be transmitted to offspring.

Some centers offer preimplantation diagnosis if both parents have known GALC gene mutations. In-vitro fertilization (IVF) is used to create embryos in the laboratory. DNA testing is performed on one or two cells taken from the early embryo. Only embryos that did not inherit Krabbe disease are implanted into the mother’s womb. This is an option for parents who want a biological child but do not wish to face the possibility of terminating an affected pregnancy.

Scientists are also researching gene therapy for Krabbe disease. This involves introducing a normal GALC gene into the cells of the affected child. The goal is for the cells to integrate the new GALC gene into its DNA and copy it, producing functional GALC enzyme. This is still in research stages and is not being performed clinically.

Prognosis Prognosis for infantile and juvenile Krabbe disease is very poor. Individuals with infantile type usually die at an average age of 13 months. Death usually occurs within a year after the child shows symptoms and is diagnosed. Children with juvenile type may survive longer after diagnosis but death usually occurs within a few years. Adult Krabbe disease is more variable and difficult to predict but death usually occurs two to seven years after diagnosis. Resources BOOKS

Wenger, D. A., et al. “Krabbe Disease: Genetic Aspects and Progress Toward Therapy.” Molecular Genetics and Metabolism 70 (2000): 1-9. ORGANIZATIONS

Treatment team The treatment team for a child with Krabbe disease should include a neurologist, general surgeon to place certain types of feeding tubes, and a hematologist if bone marrow or stem cell transplants are being considered. Physical and occupational therapists can help plan for daily care of the child and provide exercises to decrease muscle rigidity.

United Leukodystrophy Foundation. 2304 Highland Dr., Sycamore, IL 60178. (815) 895-3211 or (800) 728-5483. Fax: (815) 895-2432. . WEBSITES

Wenger, David A. “Krabbe Disease.” GeneClinics. .

Treatment Once a child with infantile Krabbe disease starts to show symptoms, there is little effective treatment. Supportive care can be given to keep the child as comfortable as possible and to counteract the rigid muscle tone. Medications can be given to control seizures. When a child can no longer eat normally, feeding tubes can be placed to provide nourishment. Affected children who are diagnosed before developing symptoms (such as through prenatal diagnosis) can undergo bone marrow transplant or stem cell transplant. The goal of these procedures is to destroy the bone marrow which produces the blood and immune system cells. After the destruction of the bone marrow, cells from a healthy donor are injected. If successful, the healthy cells travel to the bone marrow and reproduce. Some children have received these transplants and had a slowing of their symptom’s progression or even improvement of their symptoms. 468

Hunter’s Hope Foundation. PO Box 643, Orchard Park, NY 14127. (877) 984-HOPE. Fax: (716) 667-1212. .

Amie Stanley, MS Rosalyn Carson-DeWitt, MD

Kugelberg-Welander disease see Spinal muscular atrophy

❙ Kuru

Definition Kuru is the name of a progressively disabling and ultimately fatal brain infection caused by a unique protein particle called a prion.

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Key Terms Classic Creutzfeldt-Jakob disease A rare, progressive neurological disease that is believed to be transmitted via an abnormal protein called a prion.

has been traced to the ingestion of beef from cows infected with bovine spongiform encephalopathy. Known in the popular press as Mad Cow Disease.

Fatal familial insomnia A rare, progressive neurological disease that is believed to be transmitted via an abnormal protein called a prion.

Transmissible spongiform encephalopathy A term that refers to a group of disease, including kuru, Creutzfeldt-Jakob disease, Gerstmann-SträusslerScheinker syndrome, fatal familial insomnia, and new variant Creutzfeldt-Jakob disease. These diseases share a common origin as prion diseases, caused by abnormal proteins that accumulate within the brain and destroy brain tissue, leaving spongy holes.

Gerstmann-Sträussler-Scheinker syndrome A rare, progressive neurological disease that is believed to be transmitted via an abnormal protein called a prion. New variant Creutzfeldt-Jakob disease A more newly identified type of Creutzfeldt-Jakob disease that

Description Kuru was first described in a specific tribal group in Papua, New Guinea. The word “kuru” means “to shake or tremble” in this tribal group’s language. Individuals in New Guinea are believed to have acquired the infection through a cannibalistic ritual involving the blood and brains of deceased tribal members. Because infection with kuru may occur years or decades before the advent of actual symptoms of the disease, it belongs to a group of diseases originally known as slow virus infections. Currently, slow virus infections are classed together as transmissible spongiform encephalopathies (TSE). TSEs include kuru, CreutzfeldtJakob disease, Gerstmann-Sträussler-Scheinker syndrome, and fatal familial insomnia. The TSE new variant called Creutzfeldt-Jakob disease (also known colloquially as “Mad Cow Disease”) has received a great deal of public attention. The TSEs, including kuru, involve abnormal clumps of protein that accumulate throughout the brain, destroying brain tissue and leaving spongy holes.

Demographics Kuru reached epidemic proportions among tribal members in the 1950s. Since the practice of cannibalism was halted, the disease has essentially disappeared. Some sources suggest that as few as zero to 10 cases of kuru are diagnosed each year.

Causes and symptoms Kuru is caused by an infectious protein particle called a prion, which stands for proteinaceous infectious particle. A prion is similar to a virus, except that it lacks any nucleic acid, which prevents it from reproducing. Prions are abnormal versions of proteins that are found in the membranes of normal cells. These abnormal proteins can be

passed directly to individuals through the ingestion of prion-infected tissue or when open sores on the recipient’s skin are exposed to prion-infected tissue. In addition to being transmissible (as are other infectious agents like viruses or bacteria), prions are unique because they can also be acquired through genetic inheritance. Symptoms of kuru tend to begin in later middle age, years or decades after the prion was actually acquired. Early symptoms include lack of energy, intense fatigue, headache, weight loss, joint pain, difficulty walking, twitchy muscles, personality changes, mood swings, memory problems, and bizarre behavior. As the disease progresses, the individual experiences stiff muscles, involuntary movements, problems talking, hallucinations, increased confusion, blindness, and sometimes dementia. Death often occurs within three months to two years of the initial symptoms.

Diagnosis Diagnosis is arrived at through characteristic abnormalities found on the electroencephalogram (EEG), a test of brain waves and electricity. Seventy-five percent of individuals with kuru will display these specific abnormalities on EEG. MRI studies and biopsies (tissue samples) from the brain may also show changes that are characteristic of slow virus infection.

Treatment team Diagnosis of slow virus infection is usually made by a neurologist.

Treatment There are no available treatments for kuru. It is relentlessly progressive, incurable, and fatal. Supportive care for the patient and his or her family is the only treatment.

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Prognosis

Care Medicine, edited by John Noble, et al. St. Louis: W.B. Saunders Company, 2001.

Kuru is always fatal.

PERIODICALS

Resources BOOKS

Berger, Joseph R., and Avindra Nath. “Slow virus infections.” Cecil Textbook of Medicine, edited by Thomas E. Andreoli, et al. Philadelphia: W.B. Saunders Company, 2000. Murray, T. Jock, and William Pryse-Phillips.“Infectious diseases of the nervous system.” Noble: Textbook of Primary

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Sy, Man-Sun, Pierluigi Gambetti, and Wong Boon-Seng. “Human Prion Diseases” Medical Clinics of North America 86 (May 2002) 551–571. WEBSITES

National Institute of Neurological Disorders and Stroke (NINDS). Kuru Fact Sheet. Bethesda, MD: NINDS, 2003.

Rosalyn Carson-DeWitt, MD

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L ❙ Lambert-Eaton myasthenic syndrome

Definition Lambert-Eaton myasthenic syndrome is an autoimmune disease that causes muscle weakness and easy fatigability, particularly in the pelvic muscles and thighs.

Description In order to understand Lambert-Eaton myasthenic syndrome, it’s important to have some understanding of the basics of nerve transmission and stimulation of muscle movement. Nerve impulses in the body are electrical and chemical currents that travel down a nerve fiber. When they reach the end of that nerve fiber, they trigger the release of the neurotransmitter chemical acetylcholine. Acetycholine must cross a tiny gap called the synapse in order to stimulate the muscle to contract. The nerves leading to the synapse or synaptic junction are called the presynaptic nerves. In the case of Lambert-Eaton myasthenic syndrome, the body’s immune system accidentally treats specialized areas (called calcium channels) along the presynaptic nerve as if they were foreign. These calcium channels are vital to the presynaptic nerve’s ability to release acetylcholine into the synaptic junction. The immune cells attack the calcium channels as they would attack an invader such as a virus or bacteria. When the calcium channels are damaged, the release of acetylcholine into the synapse is compromised, resulting in less acetycholine being available to stimulate the muscle. Lambert-Eaton myasthenic syndrome has a very strong association with cancer, particularly small-cell lung cancer. The symptoms of Lambert-Eaton myasthenic syndrome often occur prior to diagnosis with lung cancer. In fact, about two-thirds of all people with Lambert-Eaton myasthenic syndrome will be diagnosed with some type of cancer, usually small-cell lung cancer, within two to three

years of the onset of their initial symptoms of LambertEaton myasthenic syndrome. Other types of cancer associated with Lambert-Eaton myasthenic syndrome include non-small-cell lung cancer; lymphosarcoma; malignant thymoma; and carcinoma of the breast, stomach, colon, prostate, bladder, kidney, or gallbladder. Because of the strong connection between LambertEaton myasthenic syndrome and cancer, it is sometimes considered to be a paraneoplastic syndrome (a syndrome in which substances produced by cancer cells prompt abnormalities in the body at a distance from the actual site of the malignancy). In the case of Lambert-Eaton myasthenic syndrome, it is thought that the immune system produces immune cells in response to the presence of early cancer cells. These immune cells cross-react with the calcium channels on nerve cells, resulting in the symptoms of Lambert-Eaton myasthenic syndrome.

Demographics Lambert-Eaton myasthenic syndrome is very rare, only striking about five people per every one million annually. At any one time, there are thought to be about 400 people in the United States suffering from Lambert-Eaton myasthenic syndrome. Twice as many men than women are affected, and the average age at diagnosis is about 60 years of age. Family history of Lambert-Eaton myasthenic syndrome is a known risk factor for development of the disease, as is a personal history of smoking.

Causes and symptoms In Lambert-Eaton myasthenic syndrome, the immune system accidentally attacks the calcium channels of the presynaptic nerve cells, preventing normal release of the neurotransmitter acetylcholine into the synaptic junction, and compromising the flow of nervous information between the presynaptic and postsynaptic nerves. Symptoms of Lambert-Eaton myasthenic syndrome begin with weakness and some achiness and tenderness in

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Treatment

Key Terms Acetylcholine A neurotransmitter that carries a signal from the nerve fiber to the muscle to direct contraction. Autoimmune Refers to a disease in which the body’s immune system is directed against parts of the body itself, causing damage. Paraneoplastic syndrome A syndrome in which substances produced by cancer cells prompt abnormalities in the body at a distance from the actual site of the malignancy. Plasmapheresis A procedure in which harmful cells are removed from the blood plasma. Presynaptic Before the synapse. Ptosis Eyelid droop. Synapse The gap, cleft, or junction between nerve cells or between a nerve cell and the muscle fiber.

the thigh and pelvic muscles. The upper arms may also exhibit some weakness. Due to the weak thigh and upper arm muscles, the patient’s walk may have a waddling appearance, and it may be difficult for the patient to lift his or her arms above the head. Exercise may initially improve the weakness, but the weakness may become more pronounced as exercise continues. Eyelids may droop (ptosis). Many patients notice uncomfortably dry eyes, mouth, and skin. Patients may develop difficulty chewing, swallowing, and/or speaking, as well as constipation, sudden drops in blood pressure when rising from lying down to sitting or standing, abnormalities of sweating, and erectile problems in men.

Diagnosis Lambert-Eaton myasthenic syndrome may be diagnosed by demonstrating the presence of specific antibodies in the blood that are directed against aspects of the presynaptic nerve, such as the calcium channels. Studies of nerve conduction and muscle function will reveal a variety of abnormalities. When Lambert-Eaton myasthenic syndrome is diagnosed, a search should also be done for the presence of a previously undiagnosed cancer, especially small-cell lung cancer.

Treatment team Patients with Lambert-Eaton myasthenic syndrome should be examined and then treated by both a neurologist and an appropriate cancer specialist (oncologist).

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When a cancer is identified, the first concern should be the appropriate treatment of that malignancy. Secondarily, treatment of Lambert-Eaton myasthenic syndrome may include medications to improve transmission of nerve impulses across the synaptic junction (such as pyridostigmine bromide) as well as immunosuppressant agents (such as corticosteroids, azathioprine, cyclosporine, or intravenous immungoglobulin) to decrease the immune system’s ability to further damage the presynaptic nerves. A treatment called plasmapheresis may help remove damaging immune cells from the blood.

Prognosis The prognosis of individuals with Lambert-Eaton myasthenic syndrome varies widely. In fact, the most important element of prognosis involves the prognosis associated with any existing cancer.

Special concerns Patients who develop Lambert-Eaton myasthenic syndrome should be thoroughly screened for the presence of a previously undetected cancer. If none is found, the patient should undergo regularly scheduled surveillance to monitor for the subsequent development of a malignancy. Resources BOOKS

Al-Losi, Muhammad, and Alan Pestronk. “Paraneoplastic Neurologic Syndromes.” Harrison’s Principles of Internal Medicine, edited by Eugene Braunwald, et al. New York: McGraw-Hill Professional, 2001. Gruenthal, Michael. “Lambert-Eaton Myasthenic Syndrome.” Ferri’s Clinical Advisor: Instant Diagnosis and Treatment, edited by Fred F. Ferri. St. Louis: Mosby, 2004. Posner, Jerome B.“Nonmetastatic Effects of Cancer: The Nervous System.” Cecil Textbook of Internal Medicine, edited by Lee Goldman, et al. Philadelphia: W.B. Saunders Company, 2000. PERIODICALS

Bataller, L.“Paraneoplastic neurologic syndromes. ” In Neurologic Clinics 21(1)(February 1, 2003): 221–247 WEBSITES

Lambert-Eaton Myasthenic Syndrome Fact Sheet. National Institute of Neurological Disorders and Stroke (NINDS). Bethesda, MD: NINDS, 2003.

Rosalyn Carson-DeWitt, MD

GALE ENCYCLOPEDIA OF NEUROLOGICAL DISORDERS

Definition

Laminectomy is a surgical procedure that entails opening the spinal column to treat nerve compression in the spinal cord.

Purpose Laminectomy may be performed when an abnormality causes spinal nerve root compression that causes leg or arm pain that limits activity. Numbness or weakness in hands, arms, legs, or feet, and problems controlling bowel movements or urination are indication for surgical consideration.

Precautions Before surgery, patients should refrain from medications and activities as deemed appropriate by the anesthesiologist and surgeon. These precautions can include avoidance of blood thinners such as Advil or Motrin. After surgery, there can be serious complications. Patients should go to a hospital emergency department if they develop loss of bladder or bowel control (or if they cannot urinate); if they are unable to move their legs (indicates nerve or spinal cord compression); experience sudden shortness of breath (possible blood clot in the lungs causing a condition called pulmonary embolism); or if they develop pneumonia or some other heart/lung problem.

Description Laminectomy can also be called back surgery, disc surgery, or discectomy. Laminectomy is a surgical procedure used in an attempt to treat back pain. The most common site for back pain is usually the lower back, or lumbar spine. A disc acts like a shock absorber for the spinal cord, which contains nerves that exit from foramina, or holes in a disc. A disc (or vertebral disc) is made up of a tough outer ring of cartilage with an inner sac containing a jellylike substance called the nucleus pulposis. When a disc herniates, the jellylike substance pushes through and causes the harder outer ring (annulus fibrosus) to compress a nerve root in the spinal cord. Herniation of a vertebral disc can cause varying degrees of pain. Approximately 25% of persons who have back pain have a herniated disc, causing a condition called sciatica, causing pain to be felt through the buttocks into one or both legs. The most serious compression disorder in the spinal cord is a condition called the cauda equine syndrome. The cauda equine is an area in the spinal cord where nerve roots of all spinal nerves are located. Cauda equine syndrome is a serious condition that may cause loss of all nerve function below the area of

Key Terms Annulus fibrosus A fibrous and cartilage ring that forms the circumference of a vertebrae. Lamina Flat plates of bone that form part of a vertebrae. Nucleus pulposus Central core of a vertebrae.

compression, which can cause loss of bladder and bowel control. Such a condition is a surgical emergency and immediate decompression is required without delay. Typically, conservative medical therapy is attempted for the treatment of a herniated disc. Surgery should be considered when recurrent attacks of pain cause interference with work or daily activities. The decision for surgery is indicated for chronic cases and should be made jointly between the patient and surgeon. Severe deficit can cause patients to have loss of nerve function, causing movement deficits in affected areas. Back pain is more common in men than women and more common in Caucasians than among other racial groups. Back pain results in more lost work than any other medical condition or disability. As a disorder, back pain has been documented through the ages since the first discussions date more than 3,500 years ago in ancient Egyptian writings. Laminectomy as a procedure is not exclusive to a herniated disc. Laminectomy is used for metastatic tumor invasion of the spinal cord (which causes compression), and for narrowing of the spinal cord (a condition called spinal stenosis.) In the United States, approximately 450 cases of herniated disc per 100,000 require surgery. Men are two times more likely to have back surgery as women and the average age for surgery is 40–45 years. More than 95% of all laminectomies are performed on the fourth and fifth lumbar vertebrae (lumbar laminectomy). Back pain is ranked second (behind the common cold) among the leading causes of missed workdays. Approximately one in five Americans, typically 45–64 years of age, will experience back pain. Each year, an estimated 13 million people will see their primary care practitioner for chronic back pain. Approximately 2.4 million Americans are chronically disabled from back pain, and another 2.4 million are temporarily disabled.

Description of surgical procedure Typically, the patient is placed in the kneeling position to reduce abdominal weight on the spine. The surgeon makes a straight incision over the affected vertebrae (can

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be anywhere in the spinal cord) extending to the bony arches of the vertebrae (lamina.) The surgical goal is to completely expose the involved nerve root. To expose the nerve root(s), the surgeon removes the ligament joining the vertebrae along all or part of the lamina. The nerve root is pulled back toward the center of the spinal column, and all or part of the disc is removed. Muscle is placed to protect the nerve root(s) and the incision is closed.

In-home recovery

Preparation Weeks before surgery, the surgeon (a neurosurgeon or orthopedic spine surgeon) will make a general medical assessment and establish fitness for surgery. Days before the procedure, an assessment with the anesthesiologist is necessary to discuss anesthetic options during surgery: whether to use general or spinal anesthesia. A careful history should include information about all prescription and over-the-counter (OTC) medications. Anti-inflammatory agents such as aspirin or ibuprofen (Advil, Motrin) should be stopped several days before surgery. If the patient smokes, smoking should stop at least several days before surgery. Typically, imaging studies such as x rays or magnetic resonance imaging (MRI), heart tracing studies (ECG), and routine blood work are performed before surgery. No food is permitted after midnight before surgery. Anyone undergoing surgery that lasts more than two hours may be at risk of developing a blood clot, and administering heparin (an anticoagulant) may reduce the possibility of this complication. If heparin is administered to a patient receiving laminectomy, careful monitoring and blood tests are necessary to ensure that the blood is not excessively thinned, which can cause bleeding.

Aftercare During recovery, patients will lie on a side or supine (back). There may be pain and patients will typically wear compression stockings to avoid blood-clot formation, a complication that can occur after surgery. There may be a catheter placed in the bladder to collect and measure urine output. Pain medications will be administered, and sometimes the surgeon will allow patient-controlled analgesia (PCA) with a pump that enables patients to self-deliver pain medications. Walking is encouraged hours after surgery and breathing exercises may be performed to avoid loss of air in a lung or pneumonia. It is advised to bend at the hip, not at the waist, and to avoid twisting at the shoulders or hips. The first few days after surgery may pose problems with sleeping, especially if therapeutic positions are different from normal sleeping positions. Different types of pillow positioning may be helpful (especially under the neck and knees.) To make getting out of bed easier, the patient should move the body as a unit, tighten the abdominal muscles, and roll to the side or edge of the bed and press down with 474

arms on the bed to help raise the body while concurrently and carefully swinging legs to the floor. Typically, the surgeon will schedule an appointment with postoperative patients about one week after the procedure. At about seven days, the surgeon will remove any sutures (stitches) or staples that were placed during operation. Follow-up with the personal primary care practitioner occurs within the first month after operation.

Recovery can be easier at home if patients have someone to drive for them for one or two weeks after surgery. Short, frequent walks each day may help speed recovery. Return to work is possible within one to two weeks for sedentary work, but may take more time (two to four months) if employment is strenuous with physical demands. Driving is usually not advised for one to two weeks after surgery, since postoperative medications for pain may cause drowsiness as a side effect, which can impair driving ability.

Risks After laminectomy (postoperative), there is a risk of developing complications that can include blood clots, infection, excessive bleeding, worsening of back pain, nerve damage, or spinal fluid leak. It is possible to experience drainage at the incision site, redness at the incision area, fever (over 100.4° F), or increasing pain and numbness in arms, legs, back, or buttocks. Additionally, patients may experience inability to urinate, loss of bladder or bowel control, a severe headache, or redness, swelling, or pain in one extremity. If any of these signs or symptoms appears, patients are advised to immediately call the surgeon. If the sutures or staples come out, or if the bandage becomes soaked with blood, a call to the surgeon is necessary without delay.

Normal results Some studies indicate that surgery provides better results than observation alone after one follow-up visit to the physician. However, other studies reveal that there is no statistical difference between conservative medical treatment or surgery 10 years after surgery. Resources BOOKS

Townsend, Courtney M. Sabiston Textbook of Surgery, 16th ed. New York: W. B. Saunders Co., 2001. PERIODICALS

Petrozza, Patricia H. “Major Spine Surgery.” Anesthesiology Clinics of North America 20, no. 2 (June 2002). Spivak, Jeffery M. “Degenerative Lumbar Spinal Stenosis.” The Journal of Bone and Joint Surgery 80-A:7 (July 1998).

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The American Back Society. 2647 International Boulevard, Suite 401, Oakland, CA 94601. (510) 536-9929; Fax: (510) 536-1812. [email protected]. .

Laith Farid Gulli, MD Robert Ramirez, DO

❙ Lamotrigine Definition

Lamotrigine is an anticonvulsant medication used in the treatment of epilepsy. Epilepsy is a neurological disorder in which excessive surges of electrical energy are emitted in the brain, causing seizures. Lamotrigine is usually reserved for difficult-to-control seizures that have not responded to other anticonvulsant medications. In psychiatry, lamotrigine is also indicated in the treatment of bipolar disorder (manic-depression).

Purpose While lamotrigine controls seizures associated with epilepsy, there is no known cure for the disorder. Although the precise mechanism by which lamotrigine exerts its therapeutic effect is unknown, lamotrigine is thought to act at sodium channels in the neuron (nerve cell) to reduce the amount of excitatory neurotransmitters that the nerve cell releases. Neurotransmitters are chemicals that aid in the transfer of nerve impulses from one nerve junction to the next. With decreased levels of these neurotransmitters, the electrical activity in the brain that triggers seizures is reduced. In the treatment of bipolar disorders, lamotrigine’s effect upon neurochemicals stabilizes mood, preventing sudden, unpredictable, and severe episodes of mania and depression.

Key Terms Bipolar disorder A psychiatric disorder marked by alternating episodes of mania and depression. Also called bipolar illness, manic-depressive illness. Epilepsy A disorder associated with disturbed electrical discharges in the central nervous system that cause seizures. Neurotransmitter A chemical that is released during a nerve impulse that transmits information from one nerve cell to another. Seizure A convulsion, or uncontrolled discharge of nerve cells that may spread to other cells throughout the brain, resulting in abnormal body movements or behaviors.

varying daily dosages, usually ranging 200–900 mg per day divided into two doses. Beginning any course of treatment that includes lamotrigine requires a gradual dose-increasing regimen. The safety and effectiveness of lamotrigine in children under age 18 have not been proven; therefore, the drug is seldom used in children. Adults typically take an initial dose for the first two weeks that is slowly increased over time. It may take several weeks to realize the full benefits of lamotrigine, especially in those patients taking lamotrigine for the treatment of bipolar disorders. A double dose of lamotrigine should not be taken. If a dose is missed, it should be taken as soon as possible. However, if it is within four hours of the next dose, then the missed dose should be skipped. When ending a course of treatment that includes lamotrigine, physicians typically direct patients to gradually taper down their daily dosages over a period of several weeks. Stopping the medicine suddenly may severely alter mood or cause seizures to occur, even in patients taking lamotrigine for the treatment of bipolar disorders.

Description For the treatment of epilepsy-related seizures, lamotrigine may be used alone or in combination with other anti-epileptic drugs (AEDs) or anticonvulsants. In the United States, lamotrigine is sold under the brand name Lamictal.

Recommended dosage Lamotrigine is taken orally, in either tablet or chewable form. Chewable tablets may be dispersed into a liquid solution, according to the prescribing physician’s instructions. Lamotrigine is prescribed by physicians in

Precautions A physician should be consulted before taking lamotrigine with certain non-prescription medications. Patients should avoid alcohol and CNS depressants (medications that make one drowsy or tired, such as antihistimines, sleep medications, and some pain medications), while taking lamotrigine. Lamotrigine can exacerbate the side effects of alcohol and some other medications. Alcohol may also increase the risk or frequency of seizures. Lamotrigine may not be suitable for persons with a history of liver or kidney disease, depressed renal function,

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ORGANIZATIONS

Lamotrigine

mental illness, anemia, high blood pressure, angina (chest pain), or irregular heartbeats and other heart problems. Before beginning treatment with lamotrigine, patients should notify their physician if they consume a large amount of alcohol, have a history of drug use, are nursing, pregnant, or plan to become pregnant. Lamotrigine’s safety during pregnancy has not been established. Persons taking lamotrigine (and other AEDs or anticonvulsants) should be aware that many AEDs and anticonvulsants cause birth defects. Patients who become pregnant while taking any AED or anticonvulsants should contact their physician immediately.

Side effects Lamotrigine is generally well tolerated. However, in some patients, lamotrigine may produce some of the traditionally mild side effects associated with anticonvulsants. Headache, nausea, and unusual tiredness and weakness are the most frequently reported side effects of anticonvulsants. Other possible side effects that do not usually require medical attention include: • mild coordination problems • mild dizziness

• general loss of motor skills • persistent lack of appetite • altered vision • difficulty breathing • chest pain or irregular heartbeat • faintness or loss of consciousness • persistent, severe headaches • persistent fever or pain

Interactions Lamotrigine may have negative interactions with some antacids, antihistamines, antidepressants, antibiotics, and monoamine oxidase inhibitors (MAOIs). Other medications such as HIV protease inhibitors (indinavir), ritonavir (Norvir), ipratropium (Atrovent), isoniazid, phenobarbital (Luminal, Solfoton), nefazodone, metronidazole, acetazolamide (Diamox), propranolol (Inderal), rifampin (Rifadin, Rimactane), and warfarin may also adversely react with lamotrigine. Oral contraceptives (birth control pills) may decrease the amount of lamotrigine absorbed by the body. Lamotrigine may be used with other seizure prevention medications, if advised by a physician.

• abdominal pain • sinus pain • sleepiness or sleeplessness

Resources

• diarrhea or constipation

BOOKS

Devinsky, Orrin, M. D., Epilepsy: Patient and Family Guide, 2nd ed. Philadelphia: F. A. Davis Co., 2001. Weaver, Donald F. Epilepsy and Seizures: Everything You Need to Know. Toronto: Firefly Books, 2001.

• heartburn or indigestion • aching joints and muscles or chills • unpleasant taste in mouth or dry mouth Many of these side effects disappear or occur less frequently during treatment as the body adjusts to the medication. However, if any symptoms persist or become too uncomfortable, the prescribing physician should be consulted. Other, uncommon side effects of lamotrigine can be serious and may indicate an allergic reaction. Severe and potentially life-threatening rashes have occurred during treatment with lamotrigine, occurring approximately once in every 1,000 persons who take the drug. In the unusual event that this rash develops, it normally occurs within the first eight weeks of treatment. A patient taking lamotrigine who experiences any of the following symptoms should contact a physician immediately:

OTHER

“Lamotrigine.” Medline Plus. National Library of Medicine. May 6, 2004 (June 1, 2004). . “Lamotrigine.” Yale New Haven Health Service Drug Guide. May 6, 2004 (June 1, 2004). . ORGANIZATIONS

Epilepsy Foundation. 4351 Garden City Drive, Landover, MD 20785-7223. (800) 332-1000. . American Epilepsy Society. 342 North Main Street, West Hartford, CT 06117-2507. .

• rash or bluish patches on the skin Adrienne Wilmoth Lerner

• sores in the mouth or around the eyes • depression or suicidal thoughts • mood or mental changes, including excessive fear, anxiety, hostility 476

Lateral femoral cutaneous nerve entrapment see Meralgia paresthetica

GALE ENCYCLOPEDIA OF NEUROLOGICAL DISORDERS

Definition

Learning disorders (LD) refer to a significant deficit in learning due to a person’s inability to interpret what is seen and heard, or to link information from different parts of the brain.

Description Academic deficiency is frequently associated with neurologic and psychological disorders. Severe academic problems may occur as a primary disorder of learning. Learning disorders can be classified in three major types: disorder of written expression (DWE); reading disorder (RD); and mathematics disorder (MD). The description of learning disorders corresponds to the educational legal designation of learning disabilities. Learning disabilities are legally defined by Public Law in a law called the Individuals with Disabilities Education Act, or IDEA. The IDEA defines a learning disability as a disorder in written or spoken language that results in an imperfect ability to listen, think, read, spell, write, or do mathematics. The act excludes persons who have learning impairments that are solely due to hearing problems, visual problems, motor problems, mental retardation, or due to environmental deprivation. The rules and related laws of IDEA stipulate that children with LD are entitled to free education and special services. A fourth category of LD has also been established for an LD that does not fulfill all the criteria (called an LD not otherwise specified.) Age of onset of LD is closely related to clinical presentation. Most cases of LD can be detected between preschool and second grade. Typically, onset of LD before first grade, often demonstrates developmental delay in learning new concepts at home, or as a delay in performance in school (delay is observed relative to other children and is observed by school officials). If the onset of LD occurs in early grade school (first or second grade), then observations typically include slow learning and difficulty completing and mastering schoolwork which often results in poor grades.

Demographics LD occurs in approximately 5% to 10% of the population of which about 50% are classified as reading disorder. The remaining 50% of LD falls under the categories of disorder of written expression, mathematics disorder or atypical LD. LD is more common in males than females by 2:1 or 4:1 ratio. Children with LD have an increased risk for emotional behavioral problems and comorbidity (50% of the 1.6 million children with attention-deficit hyperactivity disorder [ADHD] have an LD). Approximately 2% to 8% of elementary school children have reading disorder (dyslexia). Speech disorder occurs in

Key Terms Algorithms A sequence of steps designed to calculate or determine a task. Phoneme A discrete unit of a language that corresponds to a similar discrete unit of speech sound. Phonics A system to teach reading by teaching the speech sounds associated with single letters, letter combinations, and syllables. Rote learning Learning by means of repitition and memorization, usually without significant understanding of the concepts involved.

approximately 10% of children younger than 8 years of age. ADHD is a comorbid condition that occurs in approximately four million school-aged children (20% of them are unable to focus their attention to required tasks in school and at home).

Causes and symptoms Reading Disorder The cause of reading disorder is underactivity in the left superior posterior temporal lobe (planum temporale). Research using functional and structural neuroimaging techniques, demonstrates that this underactivity is evident during reading tasks. It is believed that the planum temporale is a region that is important for phonologic processing. Genetic studies reveal that there is a higher concordance rate for RD in identical (71%) than fraternal (49%) twins. Additionally, heritability of RD may be more than 50% especially in a disorder with a focal deficit in phonologic processing (phonologic dyslexia). Some genetic investigations have identified possible genes for RD, located on chromosome six and 15. Modern research techniques have demonstrated that RD is the result of brain deficits in processing sound units and sound-symbol relationships. Most of the persons diagnosed with reading disorder (RD) have average or higher intelligence. RD is considered synonymous with dyslexia, since spelling and reading are related. Persons with RD often have deficits with spelling. Affected individuals have difficulty with phonologic processing. This means that affected persons have deficits in the process of identifying and manipulating individual sounds (phonemes) within larger sound units (morphemes and words.) Symptoms usually appear before early grade school. Patients cannot translate a visual stimulus (letters) into a meaningful blend of sounds (i.e. they

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have deficits in phonics). Reading is slower and more mechanical even with treatment. Typically, reading takes more effort in affected patients, often requiring intense concentration, especially on the pronunciation and identification of individual words. The increased concentration required during reading can impair the person’s attention ability, causing mental fatigue, attention problems (less attention available for comprehension and memory). Sometimes, but not often, children may have visualization-comprehension or memory deficits causing RD. Persons with visualization-comprehension weakness often exhibit difficulty visualizing what is being read. The cause of visualization-comprehension weakness occurs because of deficits in visual organization (nonverbal skills.) This is a vital deficit since reading comprehension is based on some visualization (nonverbal skills.) However, in the majority of affected children with RD it is the deficits in phonologic processing (processing phonemes within morphemes and words) that are responsible for difficulty with comprehension or memory. Mathematics Disorder The cause of mathematics disorder (MD) is thought to be due to a nonverbal weakness. MD could take various forms and therefore the causes also change. There may be deficits visualizing and visually organizing mathematical concepts and manipulations. Some patients may have short-term or working memory deficits which can interfere with processing mathematical calculations. The cause of MD can be linked to a larger atypical LD. The symptoms of MD can vary. Patients can exhibit dyscalculia or acalculia (deficits in mathematical calculation). Dyscalculia patients may over-rely on memory and tangible aids, because they have deficits to mentally calculate arithmetic manipulations. Symptoms in some patients can include deficits in memory (short term and working memory or deficits in visual organization or mathematical concepts). Disorder of Written Expression The cause of the disorder of written expression in some persons may be due to deficits in visual-motor integration and motor coordination. Most causes of DWE occur because there are deficits in the brain concerning information translation from auditory-oral modality to visual-written modality. The cause of this deficit is unknown. Patients often exhibit spelling deficits that include problems with punctuation, grammar, and development of ideas during writing. Writing samples from persons with DWE are typically brief, simple, or may be difficult to comprehend because of grammar and punctuation errors. Patients with visual-motor deficits write with so much care that they often lose track of ideas and thoughts. If motor 478

coordination is the only cause then symptoms may be classified more appropriately as a motor skills disorder not a DWE. Typically symptoms are not apparent until the third or fourth grade, when academic exercises demand development of ideas.

Diagnosis The diagnosis of LD can be made if there is significant discrepancy between intelligence test scores (raw ability to learn) and achievement test score (actual learning achievement). However, the diagnosis can be a complex process since there is no universal agreement concerning the magnitude of discrepancy between test scores, nor is there a consensus concerning which test scores should be analyzed to obtain a statistical analysis of discrepancy. Tests should be administered to establish that low intelligence alone is not the cause of underachievement (i.e. children with mental retardation are not diagnosed with LDs.) There are several psychological tests that separately measure intelligence (i.e. Wechsler Intelligence Scale for Children) and achievement (Kaufman Test of Educational Achievement, K-TEA).

Treatment Team The treatment team typically includes school counselors, education specialists, specialists in learning disorders, school psychologists or clinical psychologists (with advanced clinical training in administration and interpretation of psychological tests (psychometrics). Tests for achievement and intelligence should be administered and interpreted by a clinical psychologist or a school psychologist. Only a duly licensed or certified clinical or school psychologist can administer the recommended psychological tests. A full written report of results and interpretation of results is typically prepared and submitted to concerned persons.

Treatment Before treatment is initiated, a very comprehensive evaluation is necessary with standardized achievement and intelligence tests. Treatment for RD-affected persons involves a plan that provides intensive tutoring to develop phonologic processing and fluent word reading with treatment objectives that emphasize comprehension. There are several treatment approaches (Gillingham-Stillman Approach, Fernald-Keller Approach or Lindamood-Bell Reading Program) that provide intensive phonic practice and phonic associations with sensory integration or mnemonic strategies to remember letter-sound blends and relationships.

GALE ENCYCLOPEDIA OF NEUROLOGICAL DISORDERS

Treatment for DWE can involve interventions that help to improve written expression caused by a deficit in the expressive task of writing. There are several treatment plans that include writing in more “natural environments” (i.e. encourages keeping a diary or making “lists”), writing notes and outlines before attempting writing prose, and talking-to-writing progression. The talking-to-writing progression approach initially involves the affected child taking the role of dictating while another person writes for the child. As the treatments progress, the roles are gradually reversed until the child is able to dictate and write without assistance. Treatment continues with dictation until the child is independently thinking and writing. Treatment interventions for atypical LDs involve objectives to expand on the child’s strengths (i.e. verbal and rote learning strengths) and to provide additional experience and practice in nonverbal weakness areas. Atypical LDs are complex disorders and treatment interventions are detailed and typically include teaching social and nonverbal material with extensive practice and concrete examples; teaching the affected person in rote in a predictable fashion; and the utilization and application of known algorithms to new situations. Additionally, treatment can include practicing organizational skills at home; practicing attention to visual and auditory (verbal information); and to encourage supervised and highly structured and interactive peer experiences.

Clinical trials There are many clinical trials (http://www.nlm.nih. gov) currently in progress. The studies currently sponsored by governmental agencies focus on topics that include coping, diagnosis, symptoms specific aspects of disorders, and law and public policy.

Prognosis It is rare for persons with LD to completely improve their academic deficiencies. However, performance in the area of weakness can significantly improve with appropriate treatment interventions.

Recovery Recovery is slow and patients are often in specialized intervention programs (MD, DWE) or are part of programs that offer specific treatments (RD).

Other Atypical LDs There are two common patterns of working memory deficits. Nonverbal learning disability (NVLD) is a neuropsychological syndrome characterized by deficits in comprehension, motor skills, visual-perception organization, tactile perception and novel problem solving, comprehension, visual memory, concept formation, and integration/organization of information. However, NVLD patients exhibit strengths in simple verbal skills, rote learning, memory, and knowledge of facts. In addition to weakness in mathematical achievement most persons affected by NVLD also tend to have problems with written expression, reading comprehension and social skills. Persons affected with working memory deficits tend to lose track of information as they are mentally processing that information or other information. Patients with working memory deficits often have problems with mathematical manipulations (which requires working memory), and the disorder is often accompanied by ADHD. Working memory is defined as the ability to remember information while executing another cognitive task. Resources BOOKS

Behrman, Richard, E., et al., eds. Nelson Textbook of Pediatrics, 17th ed. Philadelphia: Saunders, 2004. Goetz, Christopher G., et al, eds. Textbook of Clinical Neurology, 1st ed. Philadelphia: W. B. Saunders Company, 1999. PERIODICALS

Frank, Y., and Steven G. Pavlakis. “Brain Imaging in Neurobehavioral Disorders.” Pediatric Neurology 25, no. 4 (October 2001). Kronenberger, William G., and David Dunn. “Learning Disorders.” Neurologic Clinics 21, no. 4 (November 2003). Toppelberg, Claudio O., and Theodore Shapiro. “Language Disorders: A 10-Year Research Update Review.” Journal of the American Academy of Child & Adolescent Psychiatry 39, no.2 (February 2000). WEBSITES

National Center for Learning Disabilities. . National Institute on Deafness and Other Communication Disorders. . ORGANIZATIONS

National Institute of Mental Health, Office of Communications. 6001 Executive Boulevard, Room

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Treatment for MD can vary widely since MD can have a variety of causes and presentations. The treatment program is typically highly individualized and specific to enhance and expand upon strengths to improve weaknesses and math errors. Sometimes analogies are utilized to demonstrate abstract concepts and to build upon concepts (concrete learning) until the concept becomes understood or mastered. Flash cards and practice drills can help to memorize simple mathematical operations such as multiplication tables. MD due to visual-organization deficits can be treated with visualization techniques to improve math errors.

Lee Silverman voice treatment

8184, MSC 9663, Bethesda, MD 20892-9663. (301) 443-4513 or 1-866-615-6464; Fax: (301) 443-4279.

Laith Farid Gulli, MD Nicole Mallory

❙ Lee Silverman voice treatment

Definition Lee Silverman voice treatment (LSVT) is a technique for improving the voice volume of patients with Parkinson’s disease (PD) and other neurological disorders.

Purpose Most patients with PD experience a decreased voice volume and decreased intelligibility of their speech as their disease progresses. The purpose of LSVT is to reverse that decline by focusing the patient’s attention on increasing voice volume through an intensive set of exercises. The treatment program was developed by two speech language pathologists, and is named after one of the first patients to undergo the program.

Precautions The treatment program is entirely safe, as it consists only of vocal exercises.

well as a possible alteration in the sensory processing of sounds that is used to modulate the voice level. Despite the loss of volume, patients continue to believe their voice volume is adequate. Therefore, a key feature of LSVT is to make patients aware that their normal, pre-treatment voice level is too soft, and to help them find the correct level for normal speech. During the workshops, patients are taught methods to increase their vocal efforts by breathing more deeply and expelling air more fully and to “think shout.” Patients are trained to reach the correct volume and to selfcorrect even when they feel they are speaking too loudly. Another key feature of the program is building up the length and complexity of the vocalizations the patient is expected to deliver at the increased volume. Practice and feedback begin with single words to train the patient about the correct volume and the breath support required to produce that volume. Training moves on to simple and frequently used phrases so that the habit of loudness becomes associated with habitually used phrases. Sentences, reading aloud, and conversations follow. Repetition and reinforcement are essential parts of the program. Through constant practice and reinforcement from the therapist, the patient learns to “recalibrate” the level of effort and to become accustomed to using a louder voice than beforehand. Reinforcement from family members and others in the community is also important in solidifying the gains made during the treatment program. Patients practice with tape recorders and sound-level meters to increase the degree of feedback.

Aftercare Description The LSVT program occurs in 16 one-hour sessions given four times per week and spaced over one month. The program includes at-home exercises the patient must complete for an additional hour (two hours on non-class days). The sessions are led by specially trained speech professionals who have been certified by the LSVT Foundation, a nonprofit organization devoted to improving speech among PD patients through the LSVT method. During the sessions, patients are taught to “think loud,” that is, to focus their conscious efforts on increasing voice volume. The intensive schedule of the workshops and frequent encouragement and reinforcement from the speech professionals provide an effective training system in which the patient learns to consistently increase voice volume. Exercises to increase breath support may also be used, although for many patients, focusing on increasing the volume is sufficient. A consequence of the PD disease process is a decrease in the strength of vocal effort, due to the slowed movements and stiffness that characterize the disease, as 480

No aftercare is involved, although the patient is instructed to continue practicing the exercises learned during the treatment program.

Risks There are no risks to this treatment. Not all patients can sustain the prolonged and intense effort required in the program. Patients who have had cognitive decline may have difficulty complying with all of the instructions during training.

Normal results Patients who engage in the program dramatically increase their voice volume to return to the correct levels. They learn to be understood much better and communication renormalizes. Resources BOOKS

Ramig, L. O., S. Countryman, A. A. Pawlas, and C. Fox. Voice Treatment for Parkinson Disease and Other Neurologic

GALE ENCYCLOPEDIA OF NEUROLOGICAL DISORDERS

Key Terms

WEBSITES

Lee Silverman Voice Treatment. (April 19, 2004).

Richard Robinson

Brainstem The portion of the brain which lies between the cerebrum and the spinal cord that controls the functions of breathing, swallowing, seeing, and hearing. Mitochondria A part of the cell that is responsible for energy production.

❙ Leigh disease Definition

Leigh syndrome is an early onset, progressive neurological disease that involves defects in the normal function of the mitochondria. The mitochondrion is a small organelle located in most cells and is responsible for producing energy for cells and tissues throughout the body.

Description Leigh syndrome is caused by defective cellular respiration that supplies many tissues with energy. The disorder is severe and can be particularly difficult for family members, as infants are among the severely affected. Leigh syndrome is also known as necrotizing encephalopathy.

Demographics Leigh syndrome is a very rare disease that affects different peoples relatively equally. Some studies have shown that more males are affected than females.

Seizure A disorder of the nervous system due to a sudden, excessive, disorderly discharge of the brain neurons.

cell) in the mitochondria. Tissues that are not provided with adequate energy replenishment usually die. Irreversible damage can occur first in cells requiring much energy, such as the brain, leading to mental impairments and developmental delay. Many parts of the brain are affected by the lack of ATP in Leigh disease, including the basal ganglia, which helps regulate motor performance; the brainstem, which controls the functions of breathing, swallowing, seeing, and hearing; and the cerebellum, which coordinates balance and voluntary muscle movement. Several genetic causes explain how persons develop Leigh disease, and several genes are involved. These genes include defects found in nuclear DNA as well as the smaller, less widely known mitochondrial DNA. Genes from both genomes contribute to the normal function of the mitochondria. Mutations in genes from the nuclear and the mitochondrial DNA have both been implicated in Leigh disease.

Causes and symptoms In Leigh syndrome, symptoms usually develop within the first year of life; rarely, symptoms can develop during later childhood. The infant usually initially develops symptoms that include hypotonia (decreased muscle tone), vomiting, and ataxia (balance or coordination abnormalities). Overall, failure to grow and thrive is usually the primary reason parents seek medical help. Eventually, the infant experiences seizures, lactic acidosis (an excess of lactic acid, a normal product of carbohydrate metabolism, in the body), and respiratory and kidney impairment. Various abnormalities of the eyes are also common in Leigh syndrome. Ophthalmoplegia (paralysis of some or all of the muscles of the eye) is a typical finding, along with optic atrophy (degeneration of the optic nerve) and pigmentary retinopathy, a disorder that eventually leads to blindness. On the cellular level, persons with Leigh syndrome have an inability to produce ATP (an energy source for the

Diagnosis In general, diagnosis of Leigh syndrome is often difficult due to the broad variability in clinical symptoms as well as the many different genetic explanations that cause this disease. Genetic testing for specific nuclear or mitochondrial DNA mutation is helpful in this regard. Laboratory studies can assist in the diagnosis of Leigh syndrome. A muscle biopsy often determines if there are abnormalities associated with the mitochondria. Additionally, as the mitochondria are responsible for producing energy, a deficiency in a protein complex that has an important function in the mitochondria is often detected. In Leigh syndrome, this deficiency is found in one of five complexes that make up the mitochondrial respiratory system. One of these complexes, complex IV, or cytochrome c oxidase (COX), is commonly deficient. Although a COX deficiency is associated with Leigh syndrome, it can also indicate other mitochondrial abnormalities. Similarly,

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Disorders. Rockville: American Speech-LanguageHearing Association, 1995.

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there are mutations found in other complexes that can cause Leigh syndrome.

Treatment team Treatment for Leigh syndrome is aimed at easing the disease-related symptoms and involves neurologists, pediatricians, clinical geneticists, nurses, and other related caretakers. Psychological counseling and support for family members caring for a child with Leigh disease is often encouraged.

OTHER

“NINDS Leigh’s Disease Information Page.” National Institute of Neurological Disorders and Stroke. February 10, 2004 (April 4, 2004). . ORGANIZATIONS

The National Leigh’s Disease Foundation. P.O. Box 2222, Corinth, MS 38834. (601) 286-2551 or (800) 819-2551. United Mitochondrial Disease Foundation. 8085 Saltsburg Road, Suite 201, Pittsburgh, PA 15239. (412) 793-8077; Fax: (412) 793-6477. [email protected]. .

Treatment

Bryan Richard Cobb, PhD

Currently, there is no treatment that is effective in slowing the progression of Leigh disease. Thiamine or vitamin B1 is usually given. Sodium bicarbonate may also be prescribed to help manage lactic acidosis.

❙ Lennox-Gastaut syndrome

Recovery and rehabilitation As there is no cure for Leigh disease and the nature of the disorder is rapidly progressive, maintaining function for as long as possible is the primary focus rather than recovery. Physical therapists often assist in exercises designed to maintain strength and range of motion. As the disease progresses, occupational therapists can provide positioning devices for comfort.

Lennox-Gastaut syndrome (LGS) is one of the most severe forms of epilepsy (a seizure disorder) that develops in children usually between one and eight years old. It is characterized by several types of seizures, developmental delay, and behavioral disturbances such as poor social skills and lack of impulse control.

Description

Clinical trials As of early 2004, there are no clinical trials to treat or cure Leigh syndrome. However, studies are underway to better understand all mitochondrial diseases in an effort to identify treatments and, eventually, a cure.

Prognosis Soon after the onset of symptoms, the progression of Leigh disease is unrelentingly rapid. Death usually occurs from respiratory failure within two years following the initial symptoms, and usually by age six. Resources BOOKS

Icon Health Publicaitons. The Official Parent’s Sourcebook on Leigh’s Disease: A Revised and Updated Directory for the Internet Age. San Diego: Icon Group International, 2002. PERIODICALS

Schmiedel, J., S. Jackson, J. Schafer, and H. Reichmann. “Mitochondrial Cytopathies.” Neurol. 250, no. 3 (March 2003): 267–77. DiMauro, S., A. L. Andreu, and D. C. De Vivo. “Mitochondrial Disorders.” J Child Neurol. 17, Suppl. 3 (December 2002): 3S35–45; 3S46–47. 482

Definition

Lennox-Gastaut syndrome can be the result of any one of many neurological problems of childhood that begins with intractable, or hard to control, seizures. French physician Samuel Auguste A. D. Tissot (1728–1797) first described the syndrome in 1770. He reported an 11-yearold boy with frequent drop attacks, myoclonus (jerking movements), and progressive functional impairment. Seizure types vary among children with LGS. The tonic seizures of LGS include stiffening of the body, upward deviation of the eyes, dilation of the pupils, and altered respiratory patterns. Atonic seizures are also experienced by children with LGS and involve a brief loss of muscle tone and consciousness, which causes abrupt falls. Other seizures common in LGS include the atypical absence seizure type (staring spells) and myoclonic seizures (sudden muscle jerks). Lennox-Gastaut syndrome frequently affects language development in children, ranging from little or no verbal ability to slowness in ideation and expression. Varying degrees of motor difficulties hinder age-appropriate activities such as walking, skipping, or using a writing instrument. Severe behavioral disorders such as hyperactivity, aggressiveness, and autistic tendencies and personality disorders are nearly always present. There is usually men-

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In young children, LGS usually begins with episodes of sudden falls. In the school-age group, behavioral disturbances may be the heralding signs, along with sudden falls. This is soon followed by frequent seizures, episodes of status epilepticus (a continuous seizure state that is associated with a change in the child’s level of awareness), progressively deteriorating intellectual functions, and personality disturbances. By age six, most children with LGS have some degree of mental retardation. When children grow older, the types of seizures often change. In most cases, the drop seizures subside. They are replaced by partial, complex partial, and secondarily generalized convulsions. Among teenagers, complex partial seizures are the most common form.

Demographics

Key Terms Seizure Abnormal electrical discharge of neurons in the brain, often resulting in abnormal body movements or behaviors. Vagus nerve Tenth cranial nerve and an important part of the autonomic nervous system, influencing motor functions in the larynx, diaphragm, stomach, and heart, and sensory functions in the ears and tongue.

Symptoms The main symptom of LGS is the occurrence of seizures. Several different seizure types occur, and a child may experience some or all of these:

In the United States, Lennox-Gastaut syndrome accounts for 1–4% of older children with epilepsy, but 10% of children with epilepsy beginning in the first five years of life. In Europe, studies demonstrated that the proportion of patients with LGS seems similar to that in the US.

• In drop attacks, the child falls suddenly to the ground. This may be because the legs suddenly fold up (atonic seizure) or stiffen (tonic seizures), or because of a violent jerk (myoclonic seizure) that throws the child to the floor.

No racial differences exist in the occurrence of LGS; however there are differences in respect to sex and age. Males are affected more often than females; the relative risk of occurrence of LGS is significantly higher in boys than in girls (one in 10,000 boys, and one in 50,000 girls). The average age for the onset of seizures is three years.

• During atypical absences, the child appears to be vacant or to stare blankly. Sometimes these seizures are associated with blindness or nodding of the head. Often, children are able to continue their activity to some extent during the seizure. These episodes are usually very brief, but frequent. Sometimes these seizures occur so frequently that they merge into one another. Such a phenomenon can lead to what is called non-convulsive status epilepticus. During these episodes, children may appear to switch off, but can be partly responsive, drool, be unable to speak or eat properly, and be wobbly on their feet.

Causes and symptoms Causes Often no specific cause is identifiable, however, some of the known causes include: • developmental malformations of the brain • genetic brain diseases such as tuberous sclerosis, and inherited metabolic brain diseases • brain injury due to problems associated with pregnancy and birth, including prematurity, asphyxia, and/or low birth weight • severe brain infections, including encephalitis, meningitis, toxoplasmosis, and rubella In many instances, LGS follows earlier infantile spasms, which are sudden spasms or body bending, either at the trunk or neck. These episodes usually begin between three and eight months of age, and may develop into the mixed seizure pattern that characterizes LGS at two to three years of age.

• Tonic seizures are often difficult to detect as they occur much more frequently at night. During these attacks, there is general stiffening of the arms or legs. This may be associated with the eyes rolling up or the head moving back. Sometimes, breathing is interrupted and the child may turn blue. If the attacks last for more than 10–20 seconds, the arms often start to tremble rapidly while remaining stiff. Most children with LGS experience some degree of impaired intellectual functioning or mental retardation. In approximately 65% of children with LGS, intellectual disability is evident, either previous to or at the time of diagnosis. Behavioral disturbances are also usually present, including persistent attention-seeking behavior, impulsiveness, lack of regard for personal safety and fearlessness, and, in severe cases, autistic behaviors. These behavior disturbances may be the result of the condition

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tal retardation and sometimes a tendency for psychosis that eventually develops with LGS.

Lennox-Gastaut syndrome

causing LGS, effects of a particular medication, uncontrolled epilepsy, difficulty interpreting information, or even a lower level of concept understanding.

device may take months to show maximum benefit, and requires a surgical procedure for insertion as well as for removal. The batteries require replacement approximately every eight to ten years, which entails further surgery.

Diagnosis LGS is diagnosed by some or all of the following symptoms, including: • presence of a mixed seizure pattern • some degree of developmental delay or intellectual disability • distinct, slow, spike-and-wave pattern shown during electroencephalogram (EEG) Magnetic resonance imaging (MRI) is an important part of the search for an underlying cause in a child with LGS. Abnormalities revealed by MRI associated with LGS include tuberous sclerosis, brain malformations, or evidence of previous brain injury.

A very small percentage of children with LGS experience a spontaneous improvement in seizures, usually during adolescence. In these cases, mental function also shows some improvement. In the overwhelming majority of cases, however, emphasis is placed on maximizing quality of life rather than recovery. Protective devices such as helmets and pads may be necessary during periods of high seizure activity, but many children and parents consider them too burdensome and restrictive for continuous daily use.

Clinical trials

Treatment team Treatment for LGS involves a multidisciplinary team that may include a neurologist, a neuropsychologist, and a neurosurgeon. A dietitian may help with specialized diet regimens.

Treatment The drug treatment for LGS is based on the use of anti-epileptic drugs that are effective in reducing the number of seizures. However, the improvement often only lasts for a period of months or, rarely, a year or more. Carbamazepine, sodium valproate, vigabatrin, lamotrigine, and the benzodiazepines (clobazam, in particular) are often prescribed. One alternative treatment involves a ketogenic diet in which 87% of calories come from fat, 6% from carbohydrates, and 7% from protein. The diet is restrictive, difficult to follow, but has shown results in reducing seizures in some affected children. Other less conventional therapies such as intravenous immunoglobulin therapy have also been attempted. For children with repeated drop attacks, a procedure to cut the corpus collosum (the large group of nerve fibers connecting the two halves of the brain) may be very helpful. However, this procedure involves significant surgery and is not always effective, and seizures may return after several months or years. An implanted vagus nerve stimulator is effective in reducing seizures in many children with Lennox-Gastaut syndrome. It is a device, similar in size to a heart pacemaker, that is implanted in the chest with a lead wrapped around the vagus nerve in the neck. It is able to stimulate the vagus nerve automatically at adjustable intervals. The

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Although as of early 2004 there were no ongoing clinical trials for LGS, the National Institutes of Health (NIH) sponsors research related to many seizure disorders. Information on the numerous current clinical trials for the study and treatment of seizure disorders can be found at the NIH Web site: .

Prognosis The prognosis for individuals with LGS is unfavorable, but variable. Long-term studies of children with LGS found that a majority of patients continue to have typical LGS characteristics (mental retardation, treatment-resistant seizures) many years after onset. Children with an early onset of seizures, prior history of West syndrome, higher frequency of seizures, or constant slow EEG background activity have a worse prognosis than those with seizures beginning later in childhood. Tonic seizures may persist and be more difficult to control over time, while myoclonic and atypical absences become easier to control.

Special concerns It is recognized that the frequency of seizures may be associated with the child’s level of alertness. The child who is overexcited or lacks sufficient stimulation may experience more seizures. Therefore, a stable but stimulating environment may be important in reducing the number of daily seizures. This may include a strict routine of regular meals, sleep, and medication. Providing for the safety of a child with Lennox-Gastaut syndrome is a 24-hour concern for parents. Coupled

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Resources BOOKS

The Official Parent’s Sourcebook on Lennox-Gastaut Syndrome: A Revised and Updated Directory for the Internet Age. San Diego: Icon Group International, 2002. PERIODICALS

Frost, M., et al. “Vagus Nerve Stimulation in Children with Refractory Seizures Associated with Lennox-Gastaut Syndrome.” Epilepsia 42 (2001): 1148–1152. OTHER

NINDS Lennox-Gastaut Syndrome Information Page. National Institute of Neurological Disorders and Stroke. March 10, 2004 (May 23, 2004). .

Description Lesch-Nyhan syndrome was first described in 1964 by Dr. Michael Lesch and Dr. William Nyhan. Males with Lesch-Nyhan syndrome develop neurological problems during infancy. Infants with Lesch-Nyhan syndrome have weak muscle tone (hypotonia) and are unable to develop normally. Affected males develop uncontrollable writhing movements (athetosis) and muscle stiffness (spasticity) over time. Lack of speech is also a common feature of Lesch-Nyhan syndrome. The most dramatic symptom of Lesch-Nyhan syndrome is the compulsive self-injury seen in 85% of affected males. This self injury involves the biting of their own lips, tongue, and finger tips, as well as head banging. This behavior leads to serious injury and scarring

Demographics Lesch-Nyhan syndrome affects approximately one in 380,000 live births. It occurs evenly among races. Almost always, only male children are affected. Women carriers usually do not have any symptoms. Women carriers can occasionally develop inflammation of the joints (gout) as they get older.

Causes and symptoms

ORGANIZATIONS

Lennox-Gastaut Syndrome Group. 3872 Lyceum Avenue, Los Angeles, CA 90066. (310) 391-0335; Fax: (310) 3972687. [email protected]. Epilepsy Foundation. 4351 Garden City Drive, Suite 500, Landover, MD 20785-7223. (301) 459-3700 or (800) EFA-1000 (332-1000); Fax: (301) 577-2684. postmaster@ efa.org. . NIH/NINDS Brain Resources and Information Network. PO Box 5801, Bethesda, MD 20824. (301) 496-5751 or (800) 352-9424; Fax: (301) 402-2186. .

Greiciane Gaburro Paneto Iuri Drumond Louro, MD, PhD

❙ Lesch-Nyhan syndrome Definition

Lesch-Nyhan syndrome is a rare genetic disorder that affects males. Males with this syndrome develop physical handicaps, mental retardation, and kidney problems. It is caused by the complete absence of a particular enzyme. Self injury is a classic feature of this genetic disease.

The syndrome is caused by a severe change (mutation) in the HPRT gene. Since the HPRT gene is located on the X chromosome, Lesch-Nyhan syndrome is considered an X-linked disorder and therefore only affects males. The HPRT gene is responsible for the production of the enzyme called hypoxanthine-guanine phosphoribosyltransferase (HPRT). HPRT catalyzes a reaction that is necessary to prevent the buildup of uric acid. A severe mutation in the HPRT gene leads to an absence of HPRT enzyme activity which, in turn, leads to markedly elevated uric acid levels in the blood (hyperuricemia). This buildup of uric acid is toxic to the body and is related to the symptoms associated with the disease. Absence of the HPRT enzyme activity is also thought to alter the chemistry of certain parts of the brain, such as the basal ganglia, affecting neurotransmitters (chemicals used for communication between nerve cells), acids, and other chemicals. This change in the nervous system is also related to the symptoms associated with Lesch-Nyhan syndrome. At birth, males with Lesch-Nyhan syndrome appear completely normal. Development is usually normal for the first few months. Symptoms develop between three to six months of age. Sand-like crystals of uric acid in the diapers may be one of the first symptoms of the disease. The baby may be unusually irritable. Typically, the first sign of nervous system impairment is the inability to lift their

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with safety concerns, children with LGS are often dependent for personal care such as toileting, management of behavioral impulses, and interpretation of attempts at communication. Often, respite care can provide parents with a chance to reenergize. As the child matures into adulthood, an assisted living center or group home may help provide maximum independence and social integration, along with continued medical supervision.

Lesch-Nyhan syndrome

Lesch-Nyhan syndrome

See Symbol Guide for Pedigree Charts. (Gale Group.)

Key Terms Amniocentesis A procedure performed at 16-18 weeks of pregnancy in which a needle is inserted through a woman’s abdomen into her uterus to draw out a small sample of the amniotic fluid from around the baby. Either the fluid itself or cells from the fluid can be used for a variety of tests to obtain information about genetic disorders and other medical conditions in the fetus. Athetosis A condition marked by slow, writhing, involuntary muscle movements. Basal ganglia A section of the brain responsible for smooth muscle movement. Chorea Involuntary, rapid, jerky movements. Chorionic villus sampling (CVS) A procedure used for prenatal diagnosis at 10–12 weeks gestation. Under ultrasound guidance a needle is inserted ei-

ther through the mother’s vagina or abdominal wall and a sample of cells is collected from around the fetus. These cells are then tested for chromosome abnormalities or other genetic diseases. Enzyme A protein that catalyzes a biochemical reaction or change without changing its own structure or function. Mutation A permanent change in the genetic material that may alter a trait or characteristic of an individual, or manifest as disease, and can be transmitted to offspring. Neurotransmitter Chemical in the brain that transmits information from one nerve cell to another. Palsy Uncontrollable tremors. Spasticity Increased muscle tone, or stiffness, which leads to uncontrolled, awkward movements.

head or sit up at an appropriate age. Many patients with Lesch-Nyhan will never learn to walk. By the end of the first year, writhing motions (athetosis), and spasmodic movements of the limbs and facial muscles (chorea) are clear evidence of defective motor development.

Males with Lesch-Nyhan disease may also develop kidney damage due to kidney stones. Swollen and tender joints (gout) is another common problem.

The compulsive self-injury associated with LeschNyhan syndrome begins, on average, at three years. The self-injury begins with biting of the lips and tongue. As the disease progresses, affected individuals frequently develop finger biting and head banging. The self-injury can increase during times of stress.

The diagnosis of Lesch-Nyhan syndrome is based initially on the distinctive pattern of symptoms. Measuring the amount of uric acid in a person’s blood or urine can not definitively diagnose Lesch-Nyhan syndrome. It is diagnosed by measuring the activity of the HPRT enzyme through a blood test. When the activity of the enzyme is

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Treatment team Patients with Lesch-Nyhan syndrome should be cared for by neurologists (to monitor and treat neurological symptoms); urologists and/or nephrologists (to treat kidney stones and kidney damage); orthopedic surgeons (to treat joint problems); and psychiatrists or psychologists (to create a behavioral program).

Treatment

Mak, B. S., et al. “New Mutations of the HPRT Gene in LeschNyhan Syndrome.” Pediatric Neurology (October 2000): 332–335. Visser, J. E., et al. “Lesch-Nyhan Disease and the Basal Ganglia.” Brain Research Reviews (November 1999): 450–469. ORGANIZATIONS

Alliance of Genetic Support Groups. 4301 Connecticut Ave. NW, Suite 404, Washington, DC 20008. (202) 966-5557. Fax: (202) 966-8553. . International Lesch-Nyhan Disease Association. 114 Winchester Way, Shamong, NJ 08088-9398. (215) 6774206. Lesch-Nyhan Syndrome Registry. New York University School of Medicine, Department of Psychiatry, 550 First Ave., New York, NY 10012. (212) 263-6458. National Organization for Rare Disorders (NORD). PO Box 8923, New Fairfield, CT 06812-8923. (203) 746-6518 or (800) 999-6673. Fax: (203) 746-6481. . WEBSITES

GeneClinics . Pediatric Database (PEDBASE) .

There are no known treatments for the neurological defects of Lesch-Nyhan. The medication Allopurinol can lower blood uric acid levels. This medication does not correct many of the symptoms. Some patients with LeschNyhan syndrome have their teeth removed to prevent self-injury. Restraints are recommended to reduce self-destructive behaviors.

Holly Ann Ishmael, MS, CGC Rosalyn Carson-DeWitt, MD

❙ Leukodystrophy Definition

Prognosis With strong supportive care, infants born with LeschNyhan can live into adulthood with symptoms continuing throughout life. At present, there are no preventive measures for Lesch-Nyhan syndrome. However, recent studies have indicated that this genetic disorder may be a good candidate for treatment with gene replacement therapy. Unfortunately, the technology necessary to implement this therapy has not yet been perfected. Resources BOOKS

Jinnah, H. A., and Theodore Friedmann. “Lesch-Nyhan Disease and Its Variants.” The Metabolic and Molecular Bases of Inherited Disease. New York: McGraw-Hill, 2001. PERIODICALS

Lesch, M., and W. L. Nyhan. “A Familial Disorder of Uric Acid Metabolism and Central Nervous System Function.” American Journal of Medicine 36 (1964): 561–570.

Leukodystrophy refers to a group of rare genetic disorders affecting the central and peripheral nervous systems. They are neurodegenerative diseases characterized by abnormalities in myelin, the fatty substance that surrounds, insulates, and facilitates the function of nerve cells.

Description Leukodystrophy derives from two Greek words; “leuko” means white, referring to the white matter (myelin) of the nervous system, and “dystrophy” means abnormal growth or development. Myelin insulates, or sheaths, nerve cells, helping them to transmit electrical nerve signals. It is a complex substance composed of a number of fat and protein molecules. Without myelin, nerve cells cease to function and eventually die. It also covers the spinal cord and the long nerve cell projections, known as axons, which innervate all of the peripheral tissues.

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very low it is diagnostic of Lesch-Nyhan syndrome. It can also be diagnosed by DNA testing. This is also a blood test. DNA testing checks for changes (mutations) in the HPRT gene. Results from DNA testing are helpful in making the diagnosis and also if the family is interested in prenatal testing for future pregnancies. Prenatal diagnosis is possible by DNA testing of fetal tissue drawn by amniocentesis or chorionic villus sampling (CVS). Fetuses should be tested if the mother is a carrier of a change (mutation) in her HPRT gene. A woman is at risk of being a carrier if she has a son with Lesch-Nyhan syndrome or someone in her family has Lesch-Nyhan syndrome. Any woman at risk of being a carrier should have DNA testing through a blood test.

Leukodystrophy

Key Terms Ataxia A condition marked by impaired muscular coordination, most frequently resulting from disorders in the brain or spinal cord. Hypotonia Having reduced or diminished muscle tone or strength. Mitochondria Spherical or rod-shaped structures of the cell. Mitochondria contain genetic material (DNA and RNA) and are responsible for converting food to energy.

spinal cord). Major symptoms include weakness, numbness, paralysis, or pain in the affected area. Nystagmus An involuntary, rhythmic movement of the eyes. Organelle A specialized structure within a cell, which is separated from the rest of the cell by a membrane composed of lipids and proteins, where chemical and metabolic functions take place. Paraplegia Loss of voluntary movement and sensation of both lower extremities.

Myelin A fatty sheath surrounding nerves throughout the body that helps them conduct impulses more quickly.

Peroxisome A cellular organelle containing different enzymes responsible for the breakdown of waste or other products.

Neuropathy A disease or abnormality of the peripheral nerves (the nerves outside the brain and

Spasticity Increased mucle tone, or stiffness, which leads to uncontrolled, awkward movements.

More than 15 different types of leukodystrophy have been described, the most common of which will be discussed here. They are all caused by either an abnormality in one of the protein components of myelin, or by a defective or missing enzyme that assists in the production or normal degradation of myelin. As such, leukodystrophies are often referred to as demyelinating or dysmyelinating diseases, as well as leukoencepalopathies. Based on the part of the nervous system that is most affected, leukodystrophies may be categorized as central (brain and spinal cord), peripheral, or combined. The neurologic symptoms vary widely, both within and between the different types. All types of leukodystrophy are genetic (present at conception), progressive, and never spontaneously resolve. None of the leukodystrophies can be cured, and effective treatments are limited.

Demographics Most of the individual leukodystrophies are rare. The most common type is Canavan disease, with an incidence of about one in 8,000, followed by X-linked adrenoleukodystrophy (XL-ALD), which occurs in one in 40,000 male births. Some types of leukodystrophy are more common in certain ethnic groups, such as Canavan disease in Ashkenazi Jews, or globoid cell leukodystrophy (GLD) and metachromatic leukodystrophy (MLD) in Scandinavians. As indicated, all types of leukodystrophy are genetic, with several patterns of inheritance represented. Genes reside on the chromosomes in the nucleus of each cell; a 488

normal complement is 46 chromosomes arranged in 23 pairs. The first 22 pairs are the autosomes, and the last pair, designated X and Y, are the sex chromosomes. Males have one X and one Y, while females have two X chromosomes. One of each chromosome/gene pair is contributed by each parent at conception. Autosomal recessive inheritance refers to a disorder that only occurs if both copies of a gene pair are defective. An affected individual is typically born to unaffected parents, who each silently carry one copy of the disease gene. Each time parents who both carry the same recessive gene conceive a pregnancy, there is a 25% chance they will both transmit the disease gene and have an affected child. Autosomal dominant inheritance requires that only one copy of a gene pair be defective in order to develop the disorder. Each offspring of a parent with an autosomal dominant disorder has a 50% risk of inheriting the gene. In some conditions (e.g., Alexander disease), most cases are due to a new mutation of the gene in a sperm or egg (unaffected parent). A male who inherits the gene for an X-linked recessive disorder develops the condition because he has no normal gene on a second X chromosome to compensate for it. Female carriers of an X-linked recessive disorder are usually unaffected, but not always. If they do develop signs/symptoms, they tend to have later onset and milder symptoms. A woman who carries an X-linked recessive gene faces one of four possible outcomes with each pregnancy: affected male, unaffected male, carrier female, and noncarrier female. If an affected male has children, all of

GALE ENCYCLOPEDIA OF NEUROLOGICAL DISORDERS

Causes and symptoms All of the leukodystrophies are caused by either a defective protein component of myelin, or by a malfunctioning enzyme that interacts with one of the protein or lipid constituents. In some cases, defective, deficient, or absent myelin may cause neurons in the central or peripheral nervous system to degenerate. In other cases the neurons remain intact, but transmission of normal signals through the nerves is affected. Brief synopses of the most common leukodystrophies are provided below. Adrenoleukodystrophy (ALD), also called Addison disease with cerebral sclerosis, or melanodermic leukodystrophy, is inherited primarily as an X-linked recessive trait, but there is also a rare autosomal recessive form (neonatal ALD). X-linked ALD is caused by defects in the ABCD1 gene, also known as the ALDP (ALD protein) gene. A defective enzyme in the peroxisomes (organelles that assist in degrading substances, including some components of myelin) fails to break down very long chain fatty acids (VLCFA), which then accumulate to harmful levels in the nervous system and adrenal glands. About 35% of affected individuals have the childhood or adolescent cerebral form of ALD, which is the most severe. Age of onset ranges from four to ten years, with initial symptoms of behavioral changes, hyperactivity, and learning problems. The skin takes on a bronzed appearance due to adrenal gland dysfunction. Within several years, significant visual and auditory deficits develop, motor coordination worsens, and nearly all boys with the condition are in a vegetative state by their mid-teens. Adult adrenomyeloneuropathy (AMN) affects 30% of men with ALD, onset of symptoms may occur anywhere from adolescence to late adulthood, and progression of the disorder may occur over several decades. Adrenal dysfunction occurs first, and subsequent neurological impairments may include spastic paraplegia, peripheral neuropathy, impotence, sphincter disturbances, and hypogonadism. Approximately 10% of individuals develop an adult cerebral form, which is similar to the childhood variety, but with milder symptoms and slower progression. Another 15% have adrenal insufficiency only, and 10% of males who are positive for an ALDP gene mutation are presymptomatic at the time of testing. About 15% of carrier females develop some degree of neurologic impairment. Alexander disease is designated as an autosomal dominant condition, but most reported cases are thought to be due to new mutations in the glial fibrillary acidic protein gene (GFAP). The average age of onset in the infantile form is six months, with death by age five. Signs/ symptoms include progressive macrocephaly (large head),

psychomotor regression, spasticity, and seizures. The less common juvenile and adult forms have a slower clinical course, present with ataxia and spasticity, but usually have normal intellect. Affected adults may show relapsingremitting symptoms, similar to multiple sclerosis. The presence of Rosenthal fibers and glial fibrillary acidic proteins (GFAP) around the nerves are classic histological signs. Canavan disease, also referred to as spongy degeneration of the CNS, is autosomal recessive, secondary to mutations in the aspartoacylase gene (ASPA). Symptoms typically begin two to four months after birth, with death occurring by 10 years of age. Signs/symptoms include increased head circumference, deafness, optic atrophy, nystagmus, blindness, initial hypotonia followed by spasticity, and seizures. Cerebrotendinous xanthomatosis (CTX) is autosomal recessive, and results from mutations in the CYP27A1 gene. Large deposits of cholesterol and one of its derivatives, cholestanol, are found throughout the body, particularly the Achilles tendons, brain, and lungs. Most individuals with CTX have been diagnosed as juveniles. Signs/symptoms include cataracts and tendon xanthomas (fatty tumors) in the early stages, with ataxia, spasticity, mild mental retardation, dementia, psychiatric symptoms, respiratory insufficiency, and myocardial infarction due to atherosclerosis developing over subsequent decades. Globoid cell leukodystrophy (GLD), also known as Krabbe disease and galactocerebrosidase deficiency, is autosomal recessively inherited, and caused by defects in the glycosylceramidase (GALC) gene. The four clinical forms of GLD, based on age of onset, are infantile, late infantile, juvenile, and adult. About 90% are diagnosed with infantile GLD, with onset at several months of age, and severe neurologic deterioration progressing to death in early childhood. Signs/symptoms include deafness, blindness, irritability, episodic fever, mental deterioration, hypertonia in early stage, hypotonia later, seizures, motor deterioration, and peripheral neuropathy. The other forms of GLD vary widely in severity of symptoms and rate of progression, but those diagnosed later tend to have a better prognosis. Leigh syndrome, also called subacute necrotizing encephalopathy (SNE), refers to at least eight distinct disorders inherited as autosomal recessive or X-linked recessive traits. Another six types exhibit an unusual hereditary pattern known as mitochondrial inheritance. Mitochondria are energy producing organelles that contain their own genes. With rare exceptions, all of the mitochondria in the first cell of the embryo come from the egg. Therefore, mitochondrial inheritance resembles X-linked

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his daughters will be carriers, but none of his sons will be affected.

Carrier testing, as well as prenatal diagnosis, depends upon the availability of an established biochemical or genetic marker. The availability and accuracy of these tests are constantly changing for all genetic disorders, and the interpretation of results may be complicated. For rare disorders such as the leukodystrophies, it is especially critical to seek a consultation with a genetics counselor or geneticist to obtain the most complete and current information available.

Treatment team A neurologist manages the basic care of an individual with a neurodegenerative disorder. Given their special training and greater familiarity with these rare diseases, a geneticist would likely be consulted to make or confirm the diagnosis. The geneticist and/or genetics counselor also provides support for the family, along with the most current information on the natural history and inheritance of the disorder, options for diagnostic and prenatal testing, availability of specialized reproductive procedures, and referrals to other specialists and support groups. A diagnosis of leukodystrophy might also require involvement of neonatal intensive care unit (NICU) staff, a developmental pediatrician, occupational and physical therapists, and health professionals associated with institutional or specialized home care.

Treatment In the majority of cases, there is no effective treatment for an individual diagnosed with a leukodystrophy. However, several of the conditions do respond to specific treatments. Bone marrow transplantation has been shown to be successful in treating XL-ALD (and MLD), but only in very specific situations. The use of “Lorenzo’s oil,” a food product consisting of oleic acid, to treat XL-ALD has not been shown in multiple studies to provide any consistent benefit. Adrenal insufficiency in ALD can be successfully managed with the use of glucocorticosteroids. Effective treatment of Refsum disease is possible with a diet low in phytanic acid. Improvements in ataxia, neuropathy and ichthyosis are seen, but the diet cannot restore any vision or hearing loss that has occurred.

The use of chenodeoxycholic acid and cholic acid (CDCA), in combination with a cholesterol lowering drug, for the treatment of CTX has been successful in stopping the progression of the disease. In general, all that can be offered to most individuals with a leukodystrophy is supportive care and therapy to address their neurologic symptoms.

Clinical trials As of 2004, a primary focus for research on the treatment of leukodystrophies is on the use of stem cells from umbilical cord blood for transplantation, known as allogeneic hematopoietic stem cell transplantation. The cells are easily obtained, and are less likely than bone marrow to elicit immune system reactions in the patient. There has been some success in treating GLD, and there is hope that both XL-ALD and MLD will respond favorably as well. Both the United Leukodystrophy Foundation (ULF) and the National Institute of Neurological Disorders and Stroke (NINDS) (see below) are excellent sources of information for research being conducted on the various forms of leukodystrophy.

Prognosis The prognosis for leukodystrophy depends on the specific diagnosis. In general, a younger age of symptom onset implies a worse prognosis. With few effective treatments, and the progressive nature of hereditary, myelin-related disorders, the overall prognosis for individuals with leukodystrophy is poor. Resources BOOKS

Bradley, Walter G, et al, eds. Neurology in Clinical Practice. 3rd ed. Boston: Butterworth-Heinemann, 2000. Victor, Maurice and Allan H. Ropper. Adams’ and Victor’s Principles of Neurology. 7th ed. NewYork: The McGrawHill Companies, Inc., 2001. Wiederholt, Wigbert C. Neurology for Non-Neurologists. 4th ed. Philadelphia: W.B. Saunders Company, 2000. PERIODICALS

Kristjansdottir, R., et al. “Cerebrospinal Fluid Markers in Children with Cerebral White Matter Abnormalities.” Neuropediatrics. 32 (August 2001): 176-182. Moroni, I., et al. “Cerebral White Matter Involvement in Children with Mitochondrial Encephalopathies.” Neuropediatrics. 33 (April 2002): 79-85. Moser, H.W., et al. “X-Linked Adrenoleukodystrophy: Overview and Prognosis as a Function of Age and Brain Magnetic Resonance Imaging Abnormality. A Study Involving 372 Patients.” Neuropediatrics. 31 (October 2000): 227-239.

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Different types of leukodystrophy may mimic each other, as well as other neurodegenerative diseases (e.g., multiple sclerosis), so multiple tests could be attempted before a diagnosis is reached. A few individuals with a neurodegenerative disorder may never receive a diagnosis. A board-certified geneticist is most likely to make the correct diagnosis, using the fewest tests in the least amount of time.

Levetiracetam

Schiffmann, Raphael and Marjo S. van der Knaap. “The latest on leukodystrophies.” Current Opinions in Neurology. 17 (April 2004): 187-192. ORGANIZATIONS

Association for Neuro-Metabolic Disorders. 5223 Brookfield Lane, Sylvania, OH 43560-1809. 419-885-1497. Kennedy Krieger Institute. 707 North Broadway, Baltimore, MD 21205. 888-554-2080. . MLD Foundation. 21345 Miles Drive, West Linn, OR 97068-2878. 800-617-8387; Fax: 503-212-0159. . National Tay-Sachs and Allied Diseases Association, Inc. 2001 Beacon Street, Boston, MA 02135. 800-906-8723. . NIH/NINDS Brain Resources and Information Network. PO Box 5801, Bethesda, MD 20824. 800-352-9424. . United Leukodystrophy Foundation. 2304 Highland Drive, Sycamore, IL 60178. 800-728-5483. .

Scott J. Polzin, MS, CGC

Epilepsy A disorder associated with disturbed electrical discharges in the central nervous system that cause seizures. Neurogenic pain Pain originating in the nerves or nervous tissue. Partial seizure An episode of abnormal activity in a localized (specific) part of the brain that causes changes in attention, movement, or behavior.

assoicated with other AEDs. Levetiracetam has fewer negative interactions with other AEDs or anti-convulsants, and may be used in combination with other AEDs in the treatment of epilepsy.

Recommended dosage Levetiracetam is taken by mouth in tablet form. It is available in 250 mg, 500 mg, and 750 mg tablets. Levetiracetam is prescribed by physicians in varying total daily dosages, usually from 1000 mg to 3000 mg. Patients typically take divided doses (equal to one half of the total daily dose) twice daily.

❙ Levetiracetam Definition

Levetiracetam is an anti-epileptic drug (AED). It is often used in combination with other medications in the treatment of epilepsy, a neurological dysfunction in which excessive surges of electrical energy are emitted in the brain.

Purpose While levetiracetam controls the partial seizures (focal seizures) associated with epilepsy, there is no known cure for the disorder. In partial epileptic seizures, neural disturbances are limited to a specific region of the brain and the affected person usually remains conscious throughout the seizure. Although the precise mechanisms by which it works are unknown, levetiracetam is thought to exert its therapeutic effect by decreasing the abnormal activity and excitement within the area brain that may trigger partial seizures. Research indicates that levetiracetam may also be effective in treating neurogenic pain.

Description In the United States, levetiracetam is sold under the brand name Keppra. A newer generation medication, levetiracetam lacks many of the usual side effects commonly 492

Key Terms

Like many other AEDs, beginning a course of treatment which includes levetiracetam requires a gradual dose-increasing regimen. Adults and teenagers 16 years or older typically take 1000 mg a day for the first two weeks. Daily dosages of levetiracetam may then be increased by as much as 1000 mg every two weeks until reaching the maximum therapeutic dose (usually not more than 3000 mg). It may take several weeks to realize the full benefits of levetiracetam. It is important not to take a double dose of levetiracetam. If a dose is missed, it should be taken as soon as possible. However, if it is almost time for the next dose, then the missed dose should be skipped. When ending treatment of AEDs, including levetiracetam, physicians typically direct patients to gradually reduce their daily dosages over a period of several weeks. Stopping the medicine suddenly may cause seizures to return or occur more frequently.

Precautions A physician should be consulted before taking levetiracetam with certain non-perscription medications. Patients should avoid alcohol and CNS depressants (medications that make one drowsy or tired, such as antihistimines, sleep medications, and some pain medications)

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Levetiracetam may not be suitable for persons with a history of kidney disease, depressed renal function, or mental illness. Before beginning treatment with levetiracetam, patients should notify their physician if they consume a large amount of alcohol, have a history of drug use, are pregnant, or plan to become pregnant. Levetiracetam’s safety during pregnancy has not been established. Patients taking levetiracetam with other AEDs or anti-convulsants should be aware that many AEDs and anti-convulsants have been shown to cause birth defects in animals. Patients who become pregnant while taking any AED or anti-convulsants should contact their physician immediately.

Side effects Research indicates that levetiracetam is generally well tolerated and lacks many of the traditional side effects associated with AEDs. However, levetiracetam may case a variety of usually mild side effects in some patients. Cough, dizziness, and muscle weakness are the most frequently reported side effects of levetiracetam. Other possible side effects that do not usually require medical attention include: • dryness or soreness of throat • fever • hoarseness or voice changes

Interactions Levetiracetam is often used with other other seizure prevention medications, as prescribed by a physician. Unlike many other AEDs and anti-convulsants, levetiracetam does not decrease the effectiveness of oral contraceptives (birth control pills). Resources BOOKS

Weaver, Donald F. Epilepsy and Seizures: Everything You Need to Know. Firefly Books, 2001. PERIODICALS

Hadjikoutis, S., et. al. “Weight loss associated with levetiracetam.” British Medical Journal 327, no. 7420 (October 18, 2003): 905. Shorvon, S. D., and K. van Rijckevorsel. “A new antiepileptic drug: levetiracetam, a pyrrolidone recently licensed as an antiepileptic drug.” Journal of Neurology, Neurosurgery and Psychiatry 72, no. 4 (April 2002): 426. OTHER

“Levetiracetam (Systemic).” Medline Plus. National Library of Medicine. (April 20, 2004). ORGANIZATIONS

Epilepsy Foundation. 4351 Garden City Drive, Landover, MD 20785-7223, USA. (800) 332-1000. . American Epilepsy Society. 342 North Main Street, West Hartford, CT 06117-2507, USA. .

• sleepiness or unusual drowsiness Adrienne Wilmoth Lerner

• tender, swollen glands in neck • numbness, prickling, “pins and needles,” or tingling feelings • loss of appetite or weight loss

Levodopa see Antiparkinson drugs

Many of these side effects disappear or occur less frequently during treatment as the body adjusts to the medication. However, if any symptoms persist or become too uncomfortable, consult the prescribing physician. Other, uncommon side effects of levetiracetam can indicate a potentially serious condition. A patient taking levetiracetam who experiencs any of the following symptoms should immediately contact their physician: • clumsiness or unsteadiness • depression, paranoia, or other significant mood changes

❙ Lewy body dementia Definition

Lewy body dementia (LBD) is a neurodegenerative disorder that can occur in persons older than 65 years of age, which typically causes symptoms of cognitive (thinking) impairment and abnormal behavioral changes.

• double vision

Description

• problems with memory • lower back or side pain • painful or difficult urination • shortness of breath, wheezing, or troubled breathing.

The condition was first described by Frederick Lewy in 1941 when he described Lewy bodies, which are abnormal inclusions in the cytoplasm (components of a cell outside the nucleus) of cells found in patients who had

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while taking levetiracetam. It can exacerbate the side effects of alcohol and other medications.

Lewy body dementia

Parkinson’s disease (PD). There is some controversy concerning the relationship between Lewy body dementia and Parkinson’s disease. When cognitive impairment and behavioral disturbance are early and prominent symptoms, then LBD is the likely diagnosis. When motor symptoms are the predominant and early symptoms, then Parkinson’s disease is likely to be the diagnosis. Typically, on autopsy examination of the brain, both PD and LBD would probably demonstrate Lewy bodies. Autopsy examination is the only method to available for a definitive diagnosis. The signs and symptoms of LBD stem from a multifactorial cause of disrupted bidirectional (two-way) information flow in neurons, especially those located in the frontal lobe; that is, there are abnormalities in the chemicals that regulate and pass on message signals between neurons in the brain. Alterations in neurotransmitter chemicals can also impair nerve cell circuitry, causing abnormalities in bidirectional information flow. Most patients with LBD also have brain evidence of Alzheimer’s disease pathology. Additionally, most patients with LBD possess amyloid plaques in their cerebral cortex. Lewy bodies can also occur in a genetically transmitted form of Alzheimer’s disease, Pick’s disease, and Down syndrome.

Demographics Dementia (used as a general term) has been an increasingly common disorder that is especially more frequent in the elderly. Dementia affects 7% of the general population older than 65 years and that incidence increases with age to 30% of those age 80 years and older. Autopsy results in the United States estimate that LBD accounts for 10–20% of dementia cases. Approximately 40% of patients with Alzheimer’s disease also have LBD. Data from autopsy results in Europe and Japan reveal similar frequencies as reported in studies from the United States. No data is available concerning age, gender, or potential risk factors.

Causes and symptoms The formation of Lewy bodies is thought to occur because of an abnormal increase in the production of a normally occurring protein in nerve cells called alphasynuclein. Called upregulation, this overproduction can cause substances to accumulate or multiply in increased numbers. Other theories propose that alpha-synuclein may become insoluble (unable to mix in a watery environment), which could make the molecule more prone to accumulate abnormally in the brain. Symptoms can include cognitive impairment, neurological signs, sleep disorder, and autonomic failure. Cognitive impairment is the presenting feature of LBD in most cases. Patients have recurrent episodes of confusion that 494

progressively worsen. The fluctuation in cognitive ability is often associated with shifting degrees of attention and alertness. Cognitive impairment and fluctuations of thinking may vary over minutes, hours, or days. Psychological manifestations Psychological manifestations of LBD predominantly include: • delusions, false beliefs, or wrong judgments held to be true despite incontrovertible evidence to the contrary • visual hallucinations, strong subjective perception of an imaginary event or object • apathy, an indifference or absence of interest in the environment • anxiety, apprehension, or dread that causes symptoms of rapid heart rate, restlessness, tension, and shortness of breath Neurological symptoms in patients affected with LBD include extrapyramidal features early in the disease. The extrapyramidal symptoms in LBD can be differentiated from other dementias such as Parkinson’s disease. Patients affected with LBD tend to show axial involvement with greater postural instability and facial impassivity, and less tremor. Disorders of sleep in patients with LBD typically can include impairment of rapid-eye-movement (REM) sleep; REM sleep behavior disorder causes vivid and frightening dreams. Patients may also exhibit loss of muscle tone or cataplexy, hypersomnolence (an increased inclination to sleep), hallucinations, and narcolepsy. Patients with LBD also have deficits in the autonomic nervous system, part of which regulates specific body functions such as blood pressure and bladder control. Autonomic abnormalities can cause orthostatic hypotension and urinary incontinence.

Diagnosis Clinically, patients have features of fluctuating cognitive impairment such as from alert to confused state, recurrent visual hallucination, depression, and REM sleep disorder. Patients may have impairment of memory retrieval and they often do poorly on tests that measure visuospatial skills such as copying figures or drawing a clock. Patients may have mild gait (walking) impairment. An accurate diagnosis can include identification of target symptoms, including cognitive impairment, psychological disorders (hallucinations, depression, sleep disorder, and behavioral disturbances), extrapyramidal motor features or autonomic dysfunction (orthostatic hypotension), or urinary incontinence. Standard blood tests are ordered and additional tests are typically required, including thyroid studies, vitamin B-12 levels, and, if appropriate, tests for Lyme disease, syphilis, or HIV since these infections can affect the brain. Currently, there are no specific tests used

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Alzheimer’s disease A neurodegenerative disorder that causes nerve-cell death and symptoms that typically include loss of thinking and language ability, and memory impairment. Autonomic failure Refers to failure in the autonomic nervous system, which comprises two divisions called the parasympathetic nervous system, which slows heart rate, increases intestinal and gland activity, and relaxes sphincter muscles; and the sympathetic nervous system, which accelerates heart rate, raises blood pressure, and constricts blood vessels. Cataplexy A sudden loss of muscle tone. Dementia A progressive loss of intellectual functions without impairment of consciousness or perception. The condition is often associated with brain disease and persons exhibit symptoms such as disorientation and impaired memory, judgment, and intellect. Down syndrome A genetic disorder, also called trisomy 21, characterized by mental retardation, heart defects, slanting eyes, short fingers, broad short skull, and broad hands.

to diagnose LBD. A magnetic resonance imaging (MRI) scan is indicated to distinguish LBD from another disorder called vascular dementia, which can present with similar clinical signs and symptoms. It is important to exclude diseases or drugs that can cause delirium.

Treatment team The treatment team can be broad, including general practitioners, geriatric psychotherapists, emergency services, or movement disorder specialists. Additionally, the team can include family members, primary care practitioners, caregivers, and neurologists. Special consultations from a neurologist with special expertise in dementias may be appropriate for caregiver education.

Treatment The management of LBD can be approached in four stages: accurate diagnosis, identification of target symptoms, nonpharmacological treatment, and pharmacological treatment. Nonpharmacological interventions include management of environment and other necessities associated with LBD patient care. Caregiving skills should be specifically tailored to the patient. Pharmacological treatment can include several different medications, most notably a class of drugs called cholinesterase inhibitors.

Hallucinations False perceptions that can occur without a true sensory stimulus. Narcolepsy A genetically determined disorder characterized by recurrent episodes of daytime sleep, disrupted nighttime sleep, cataplexy, hallucinations, and sleep paralysis. Orthostatic hypotension A fall in blood pressure due to a change in body position, usually from the sitting position to an erect or standing position. Parkinson’s disease A neurodegenerative disorder that results in changes to neurons in the brain stem, causing affected persons to have symptoms that include a resting tremor, speech impairments, movement disorders, shuffling walk, stooped posture, and dementia. Pick’s disease A neurological degenerative disorder that causes deterioration of social skills and personality, and causes impairment of memory, language, and intellect. Urinary incontinence Unable to control urinary excretion.

These medications tend to increase a brain neurochemical called acetylcholine, which is an excitatory brain chemical that is decreased in persons with LBD. With a typical dose of a cholinesterase inhibitor (Donepezil or Aricept), the symptoms of visual hallucinations, apathy, anxiety, sleep disorder, and cognitive impairments can be improved. Generally, medications can be utilized to slow the rate of cognitive decline, treat agitation and hallucinations, treat depression, and improve cognition and/or alertness.

Recovery and rehabilitation Generally, there are no dietary restrictions for persons affected with LBD, except for those who have swallowing impairment. Physical therapy and an exercise program can be useful to maintain mobility. There are potential problems for patients who drive a motor vehicle, and family members and caregivers should be advised.

Clinical trials Currently, the National Institute of Neurological Disorders and Stroke (NINDS) supports research concerning diagnosis, prevention, and treatment. Research efforts studying the biological consequences of Lewy body formation and mechanisms of disease progression are funded by NINDS.

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Key Terms

Lidocaine patch

Prognosis LBD is a slowly progressive chronic disorder. However, the rate of progression may be faster than in Alzheimer’s disease. The disease is fatal from complications of poor nutrition, swallowing difficulties, and immobility.

Special concerns Primary caregivers and family members require information concerning management of symptoms such as hallucinations, agitation, and cognitive changes. Children of patients with LBD may require genetic counseling. Family members should be aware that LBD affects job performance and medical leave of absence or early retirement may be advisable. Driving may become problematic and should be addressed with the medical treatment team, patient, and family. Resources

Purpose The lidocaine patch relieves pain and discomfort by blocking signals sent to nerve endings in the skin. Almost 20% of the one million Americans who develop shingles yearly experience long-term pain after the infection has resolved. People over age 60 are especially prone to postherpetic neuralgia.

Description

BOOKS

Goetz, Christopher G., et al, eds. Textbook of Clinical Neurology, 1st ed. Philadelphia: W. B. Saunders Company, 1999. Goldman, Lee, et al. Cecil’s Textbook of Medicine, 21st ed. Philadelphia: W. B. Saunders Company, 2000.

The lidocaine patch is composed of an adhesive material containing 5% lidocaine that is applied to a polyester felt backing. When it is applied to the skin, lidocaine is released into the epidermal and dermal layers of the skin, reducing pain at the site of the dysfunctional nerves damaged by the prior herpes zoster infection. The lidocaine patch provides pain reduction without numbness of the affected skin.

PERIODICALS

McKeith, Ian. “Dementia with Lewy bodies.” The Lancet Neurology 3, no. 1 (January 2004). WEBSITES

Crystal, Howard A. eMedicine—Dementia with Lewy Bodies. November 11, 2003 (May 23, 2004). . Lewy Body Dementia. (May 23, 2004). National Organization for Rare Disorders (NORD). (May 23, 2004). ORGANIZATIONS

National Institute on Aging, National Institutes of Health. Building 31, Room 5C27, Bethesda, MD 20892-2292. (301) 496-1752. .

Laith Farid Gulli, MD Robert Ramirez, DO Nicole Mallory, MS, PA-C

❙ Lidocaine patch

In the United States, the lidocaine patch is sold under the name of Lidoderm.

Recommended dosage The lidocaine patch is available in varying doses. Patches are applied directly to healthy, non-broken skin close to the source of pain or discomfort. Patients may typically apply up to three patches at one time. However, patches should not be worn longer than 12 hours in a 24hour period. Patches can be cut into smaller pieces before removing the release liner and applying to the skin. Clothing may be worn over the applied patch. If a dose is missed, it should be taken as soon as possible. However, if it is almost time for the next dose, then the missed dose should be skipped. More patches than are instructed by the prescribing physician should never be applied.

Precautions

Definition

Lidocaine belongs to a class of local and topical anesthetic medications. As lidocaine causes a temporary numbness or loss of sensation when injected in the tissues, it is used as a local anesthetic and in the treatment of pain. 496

When given intravenously, lidocaine is also an antiarrythmic agent, capable of correcting some ventricular arrythmias of the heart. The lidocaine patch is a topical treatment that is especially helpful in the treatment of pain associated with postherpetic neuralgia, a condition that can occur after infection with the herpes varicella zoster (shingles) virus. Additionally, the lidocaine patch is sometimes used in the treatment of some chronic forms of nerve pain such as the pain associated with fibromyalgia.

Lidocaine may not be suitable for persons who have had a past reaction to any local anesthetic. Patients should discuss past adverse reactions to anesthetics with their physician before using the lidocaine patch. The lidocaine

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Key Terms Herpes varicella zoster virus The virus that typically causes chicken pox in children; then may reactivate later in life to cause shingles.

• ringing or buzzing in the ears • uncontrollable nervousness, shaking • slow heartbeat

Topical For application to the surface of the skin.

patch may also not be suitable for persons with a history of severe liver disease. Additionally, the lidocaine patch should be used with caution in persons receiving antiarryhthmic drugs. Hand-washing is important after handling or applying the lidocaine patch. Contact with eyes should be avoided. The zipper pouch containing the lidocaine patches should be completely closed after opening, as the patches will lose potency if allowed to dry. Patches can be cut with scissors to the size and shape necessary to fit facial areas, but care should be used not to allow the material in the lidocaine patch to enter the eye. The lidocaine patch should never be chewed or ingested, or used to relieve pain inside the mouth.

Lissencephaly

• blurred or double vision

Interactions As the lidocaine patch is topical treatment and only minute amounts of the drug are absorbed into the bloodstream, interactions with other drugs are few. The lidocaine patch may have rare negative interactions with digoxin (Lanoxin) or any medications for irregular heartbeats. Some antibiotics, antidepressants, and monoamine oxidase inhibitors (MAOIs) may adversely react with the lidocaine patch or lessen its effectiveness. Resources PERIODICALS

Alper, B. S., and P. R. Lewis. “Treatment of Postherpetic Neuralgia: A Systemic Review of the Literature.” Journal Fam. Pract. (2002): 51: 121–8. Argoff, C. E. “New Analgesics for Neuropathic Pain: The Lidocaine Patch.” Clin. Journal Pain (2000): 16: S62–66. Watson, C. P. “A New Treatment for Postherpetic Neuralgia.” New England Journal Med. (2000): 343: 1563–65. OTHER

Side effects As only minute amounts of lidocaine enter the bloodstream from the patch, side effects are few. Most patients tolerate normal use of the lidocaine patch well, but some patients may experience usually mild side effects. Localized tingling may occur. If a rash or burning sensation occurs after application, the patch should be removed and not reapplied until the irritation subsides. If any symptom becomes uncomfortable, patients should consult the prescribing physician.

“Lidocaine Patch Effective in Relieving Nerve Pain After Shingles.” The Doctors’ Guide. June 4, 1999. May 13, 2004 (June 1, 2004). . “Lidocaine Transdermal.” Medline Plus. National Library of Medicine. .

Adrienne Wilmoth Lerner

Some patients may be allergic to topical lidocaine and the lidocaine patch. Medical treatment should be sought immediately if any of the following symptoms occur:

❙ Lissencephaly Definition

• cough • difficulty breathing or swelling of the tongue • dizziness, fainting, or loss of consciousness • hives or swelling of the face • trouble breathing Other less common side effects of the lidocaine patch may be serious, potentially indicating that too much medication is being absorbed into the body. A patient should seek medical treatment if experiencing: • excessive, all-over numbness

Lissencephaly is a neurological disorder of early brain development that leads to the gross appearance of a smooth brain. The malformed brain lacks the characteristic convolutions of the normal cerebral cortex and is abnormally thick. Lissencephaly is part of a spectrum of brain malformations, which are referred to as the agyriapachygyria-band spectrum and are caused by abnormalities in neuronal migration, a critical process in brain development. These disorders range from complete absence of folds (agyria) to milder forms such as subcortical band heterotopia or double cortex syndrome, a neurological disorder where the malformed brain has two distinct

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Lissencephaly The disconnected hemispheres of a brain affected with agenesis of the corpus callosum. (Custom Medical Stock Photo. All Rights Reserved.)

layers of cerebral cortex. In pachygyria, there are localized areas of abnormally large folds and, in general, it is less severe than agyria. Scientific research on mice and humans has revealed several important genes responsible for causing lissencephaly.

Description Lissencephaly was first described by Owen in 1868 and means “smooth brain,” which describes the gross appearance of the brain. Microscopically, the brain appears abnormally thick and disorganized. The layering of the cerebral cortex is grossly abnormal, with four layers instead of the normal six layers. Lissencephaly can be divided into two main subtypes. Type I, also known as classical lissencephaly, is distinguished by the smooth surface of the cerebral cortex and an abnormal four-layered cortex. Classical lissencephaly can be associated with abnormalities of the rest of the brain, including malformation of the corpus callosum or 498

cerebellum. Lissencephaly can also be associated with other developmental abnormalities such as facial deformities in a syndrome known as the Miller-Dieker syndrome. Type II, or “cobblestone” lissencephaly, is characterized by a bumpy appearance of the abnormal surface of the brain. The cortex in Type II lissencephaly is completely abnormal and there are no distinguishable layers. This subtype tends to be associated with genetic syndromes affecting muscles, as in the Walker-Warburg syndrome. Different genes and distinct processes are thought to be responsible for causing the two types of lissencephaly.

Demographics Type I lissencephaly is more common and comprises 43% of lissencephaly syndromes in some studies. Type II lissencephaly accounted for 14% of lissencephalies. The remainder in these studies were comprised of various disorders such as pachygyria.

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Cerebral cortex The layer of gray matter that makes up the surface of cerebral hemispheres of the brain. It is responsible for controlling sensation, movement, and higher cognitive functions.

Causes and symptoms Lissencephaly is due to a defect in neuronal migration, a sequence of events in early brain development in which nerve cells travel to their final destinations to populate and form the six layers of the cerebral cortex. This process occurs between 12 and 16 weeks gestation. When the brain first forms, neurons are generated in a region of the brain known as the ventricular zone. From there, they travel by crawling outward along other cells, known as radial glia, to reach the cortical surface. The traveling neurons need instructions on when to start, continue, and stop moving, and these processes are controlled by a complicated molecular machinery. Several genes have been implicated in causing lissencephaly, and their roles in neuronal migration are currently being characterized. The first gene causing lissencephaly, LIS1, was identified in patients with Miller-Dieker syndrome, a genetic syndrome caused by deletions of chromosome 17 that is a combination of lissencephaly and other facial deformities. So far, five genes have been identified that cause type I lissencephaly in humans. Among them, LIS1, DCX, and RELN have been implicated as important at various steps during neuronal migration. DCX, a gene on the X-chromosome, is responsible for the double cortex syndrome, a milder subtype of lissencephaly, which has the unusual appearance of a brain with two layers of cerebral cortex, one normal and one abnormally situated in the white matter. This abnormal layer, called a band heterotopia, represents the neurons that have started and failed to migrate completely to their destination. For type II lissencephaly, only one gene, fukutin, has been identified. Presumably, the disorder in type II lissencephaly is an abnormal overmigration of neurons, which causes nerve cells to accumulate beyond the cortical surface, leading to the cobblestone appearance. Other nongenetic causes of lissencephaly include cytomegalovirus infection. Babies with lissencephaly may appear normal at birth, but then progress to severe developmental delay, seizures, and failure to thrive at several months of age. There may be abnormally small head size, known as microcephaly. Seizures are usually difficult to treat and start out in the first few months of life. Patients may also develop cerebral palsy and decreased muscle tone. Patients

Diagnosis Diagnosis is usually made by neuroimaging. A computer tomography (CT) or magnetic resonance imaging (MRI) scan shows a smooth brain with the lack of characteristic folds. MRI may delineate the band of abnormal nerve cells in the double cortex syndrome. MRI may also show abnormalities in other areas of the brain in certain forms of lissencephaly. Genetic testing can be performed in patients with lissencephaly to identify abnormalities in the LIS1 or DCX gene.

Treatment team Management of lissencephaly usually involves a pediatrician, pediatric neurologist, and physical therapists. A geneticist may be involved to provide counseling and advice about family planning. Depending on the age of onset of symptoms, an adult neurologist may be involved in treating symptoms of seizures. A case manager may be involved in coordinating the different care needs of the patient and families.

Treatment Currently, there is no cure for lissencephaly. Treatment of individuals with lissencephaly depends on the manifesting symptoms. Patients may need anticonvulsant drug therapy for treatment of seizures. Muscle relaxants may be used for symptoms of increased tone.

Recovery and rehabilitation Due to the congenital nature of lissencephaly, patients show little recovery from their symptoms. Physical therapists may help treat symptoms of weakness or increased tone associated with lissencephaly.

Clinical trials A clinical trial is currently ongoing and is funded by the National Institutes of Health to identify genes responsible for neuronal migration disorders such as lissencephaly and schizencephaly.

Prognosis There is no known cure for lissencephaly. Most individuals will die at an early age due to failure to thrive or infections such as pneumonia. Patients with milder forms such as double cortex syndrome may have mild retardation

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Key Terms

with milder forms such as double cortex syndrome may not develop symptoms until later in early childhood. They may have only mild developmental delay and seizures without microcephaly.

Locked-in syndrome

and seizures only. The response to treatment varies from individual to individual.

Walsh Lab Web Site. 4 Blackfan Circle, Boston, MA 02115. (617) 667-0813; Fax: (617) 667-0815. cwalsh@ bidmc.harvard.edu. .

Special concerns

Peter T. Lin, MD

Due to developmental disability, children with lissencephaly who survive beyond the age of two may benefit from special education programs. Various state and federal programs are available to help individuals and their families with meeting these needs.

Definition

Resources BOOKS

Menkes, John H., MD, and Harvey Sarnat, MD, eds. Childhood Neurology, 6th edition. Philadelphia: Lippincott Williams & Wilkins, 2000. “Congenital Anomalies of the Nervous System.” Nelson Textbook of Pediatrics, 17th edition, edited by Richard E. Behrman, MD, Robert M. Kliegman, MD, and Hal B. Jenson, MD. Philadelphia: Saunders, 2004. PERIODICALS

Gleeson, J. G. “Neuronal Migration Disorders.” Mental Retardation and Developmental Disabilities Research Reviews 7 (2001): 167–171. Guerrini, R., and R. Carrozzo. “Epilepsy and Genetic Malformations of the Cerebral Cortex.” American Journal of Medical Genetics 106 (2001): 160–173. Kato, M., and W. B. Dobyns. “Lissencephaly and the Molecular Basis of Neuronal Migration.” Human Molecular Genetics 12 (2003): R89–R96. Ross, M. E., and C. A. Walsh. “Human Brain Malformations and Their Lessons for Neuronal Migration.” Annual Review of Neuroscience 24 (2001): 1041–1070. WEBSITES

National Institutes of Neurological Disorders and Stroke (NINDS). Cephalic Disorders Information Page. (February 19, 2004.) . ORGANIZATIONS

Lissencephaly Network. 10408 Bitterroot Court, Ft. Wayne, IN 46804. (260) 432-4310. [email protected]. . March of Dimes Birth Defects Foundation. 1275 Mamaroneck Avenue, White Plains, NY 10605. (914) 428-7100 or (888) MODIMES; Fax: (914) 428-8203. askus@ marchofdimes.com. . National Information Center for Children and Youth with Disabilities. P.O. Box 1492, Washington, DC 20013-1492. (202) 884-8200 or (800) 695-0285; Fax: (202) 884-8441. [email protected]. . National Institute of Child Health and Human Development (NICHD). Bldg. 31, Rm. 2A32, Bethesda, MD 208922425. (301) 496-5133 or (800) 370-2943. [email protected]. . 500

❙ Locked-in syndrome Locked-in syndrome is a condition in which an individual is fully conscious, but all the voluntary muscles of the body are completely paralyzed, with the exception of the muscles controlling eye movement.

Description Locked-in syndrome is a catastrophic condition that prevents an individual from voluntarily moving any muscles of the body, other than those that control eye movement. As a result, the individual cannot move or speak, although some communication is possible through blinking or eye movements. Despite the devastating loss of function, an individual with locked-in syndrome is completely conscious and aware, able to think and reason normally. Luckily, locked-in syndrome is exceedingly rare. About 40–70% of people suffering from locked-in syndrome die within a short time of suffering the causative injury.

Causes and symptoms Locked-in syndrome can occur after severe, catastrophic brain injuries due to massive stroke, traumatic head injury, or ruptured aneurysm. Diseases that destroy the myelin sheath around nerves and the toxic effects of medication overdose can also cause locked-in syndrome. The most common cause involves any condition that affects an area of the brain called the ventral pons; all of the nerve tracts responsible for voluntary movement pass through the ventral pons. Areas of the brain responsible for cognition and consciousness are above the level of the ventral pons, and are therefore preserved. Symptoms include complete inability to control any voluntary muscles in the body, other than those for eye movements and blinking. Reasoning, thinking, consciousness, and awareness are preserved. Normal sleep and wake cycles persist throughout the locked-in state.

Diagnosis Diagnosis is evident in a conscious individual with no muscle functioning, save for the ability to respond to questions by blinking a certain number of times per the

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Lou Gehrig disease see Amyotrophic lateral sclerosis Lumbar radiculopathy see Radiculopathy

Treatment team Patients with locked-in syndrome are cared for by critical care specialists, neurologists, and physiatrists. A variety of therapists may also work with such patients, including physical therapists, occupational therapists, speech and language therapists, and psychotherapists.

Treatment

❙ Lupus Definition

Lupus, also known as lupus erythematosus, is an autoimmune inflammatory disorder that occurs mostly in women.

There is no cure for locked-in syndrome. Treatment is supportive.

Recovery and rehabilitation One of the most important goals of rehabilitation involves finding assistive devices that can help with communication. A technique of stimulating muscle groups with electrodes (called functional neuromuscular stimulation) sometimes can help restore some small degree of functioning; however, even being able to move one finger can greatly improve an individual’s ability to communicate or operate assistive devices that could improve that person’s level of functioning.

Prognosis Locked-in syndrome has a very poor prognosis, although some individuals have lived as long as 18 years with the condition.

Special concerns Ethical dilemmas regarding the treatment and wishes of patients with locked-in syndrome are complicated. Resources BOOKS

Hammerstad, John P. “Strength and Reflexes.” In Textbook of Clinical Neurology, edited by Christopher G. Goetz. Philadelphia: W. B. Saunders Company, 2003. Simon, Roger P. “Coma and Arousals of Disorder.” In Cecil Textbook of Internal Medicine, edited by Lee Goldman, et al. Philadelphia: W. B. Saunders Company, 2000. PERIODICALS

Hayashi, H. “ALS patients on TPPV: totally locked-in state, neurologic findings and ethical implications.” Neurology 61, no. 1 (July 2003): 135–137.

Rosalyn Carson-DeWitt, MD

Description Lupus produces widely varying symptoms, although joint pain is reported by most patients and skin lesions are common. Lupus can cause short periods of symptoms alternating with healthy periods, or can progress into a lifethreatening disorder affecting the heart, kidneys, and other organs. Why the disease is termed lupus is unknown, but it has been known as a distinct disorder and called lupus by European physicians since at least the tenth century A.D. The term erythematosus was first attached to the disease in the 1850s, and it refers to the patchy congestion of skin capillaries with blood (erythema) that often accompanies the disease.

Demographics Between one million and 1.5 million Americans have some form of lupus. The incidence among women is 10–15 times greater than among men, and it is two to three times more common among African Americans, Hispanics, Asians, and Native Americans than among whites. Lupus most often appears for the first time in women between the ages of 15 and 44. Twenty thousand people die of lupus-related causes in the United States annually.

Causes and symptoms Lupus is an autoimmune disorder, a disease in which the body’s immune system turns against the body itself. In a healthy person, the immune system defends against invading organisms but does not, in general, attack the body’s own tissues. The cause of lupus is unknown. However, it is known that lupus has a genetic component, which means a predisposition to lupus can be inherited. Approximately 10% of lupus patients have one or more direct relatives with lupus. (Note that this means that 90% of lupus patients have no such relatives; however, it shows a

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interviewer’s directions. Further diagnostic tests will be required to determine the underlying cause of the condition; CT or MRI scans can reveal the presence of an aneurysm or stroke.

Lupus Systemic lupus erythematosus (SLE) is an autoimmune disease in which the individual’s immune system attacks, injures, and destroys the body’s own organs and tissues. Nearly every system of the body can be affected by SLE, as depicted in the illustration above. (Illustration by Electronic Illustrators Group.)

Key Terms Autoimmune disorder A disorder characterized by abnormal functioning of the immune system that causes the body to produce antibodies against its own tissues. Cutaneous Relating to the skin. Erythema Redness of the skin due to congestion of the capillaries, usually due to injury, infection, or inflammation.

genetic connection because 10% is a much higher figure for familial lupus than can be attributed to chance alone.) Lupus has been definitely linked to genes on chromosome 1 and less certainly to genes on chromosomes 4 and 6. 502

Given genetic susceptibility, the disease may either develop spontaneously or be triggered by some environmental factor. Environmental factors known to trigger lupus include infections (e.g., Epstein-Barr virus, which infects 99% of children with lupus, but only 70% of healthy children), antibiotics, ultraviolet light (the rays in sunlight or sunlamp-light that causes sunburn), stress, smoking, certain medications, and hormones (especially estrogen, the female sex hormone). Lupus manifests as a continuum or spectrum of disorders. However, it is common to divide lupus cases into four categories or groups: • Systemic lupus erythematosus. This is the most serious form of lupus and affects about 70% of all persons with lupus. It is termed systemic because, in this variety of lupus, the body’s immune system attacks one or more essential body systems. Targets may include the brain, kidneys, heart, pancreas, or other organs.

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• Drug-induced or drug-related lupus erythematosus. This term refers to lupus that develops after a patient has taken a medication. Medications that can trigger drug-induced lupus include procainamide or hydralazine. Many of the substances that can potentially trigger lupus fall into the class of aromatic amines, or hydrazines. For example, the aromatic amine paraphenylenediamine is present in certain hair dyes and has been associated with lupus or lupus-like syndrome. Tartrazine (a food coloring, FD&C yellow No. 5), which is present in thousands of foods and medications, has also been associated with lupus. Cocaine abuse can induce lupus and several other connective-tissue diseases, as can exposure to certain metals (e.g., mercury). Between 10,000 and 15,000 people are diagnosed with drug-induced lupus annually in the United States. • Mixed connective tissue disease. Approximately 10% of patients with lupus also have symptoms of one or more additional connective-tissue diseases. The symptoms of lupus are quite varied. In discoid lupus, red patches (erythema) appear symmetrically on the cheeks, possibly extending to the face, neck, scalp, and other parts of the body. No organ other than the skin is affected (or the disease is classified as systemic, rather than discoid). Systemic lupus may begin suddenly, signaled by fever, or develop slowly over months or years. Chronic fatigue is a common symptom. Symptoms related to impairment of any organ may occur. The lupus disease process in a given organ is named after that organ; for example, inflammation of the kidneys is termed lupus nephritis, and inflammation of the brain is termed lupus cerebritis. Kidney involvement may be fatal. Over 50% of all systemic lupus patients in the United States presently have some degree of lupus cerebritis; 25–75% have neuropsychiatric symptoms at some time in their illness. Symptoms of lupus cerebritis may include headaches, seizures, stroke, psychosis, dementia, peripheral neuropathy, cerebellar ataxia (failure of muscular coordination, usually on one side of the body), chorea (jerky, involuntary movements), and others. Duration of central nervous system involvement may be transient (as with a migraine headache) or long lasting (as with dementia). Stroke incidence is 3–20% in systemic lupus patients, and is highest in the first five years of the disease. Peripheral neuropathy (carpal tunnel syndrome, for example) occurs in more than 20% of systemic lupus patients and cranial nerve palsies occur in 10–15%.

Exposure to the ultraviolet rays in sunlight can trigger lupus or, in a person who already has the disease, cause it to flare up. Worsening flare-ups of the disease can be life threatening because they can include inflammation and failure of the kidneys. Also, declining memory and mental sharpness with long-term lupus is common.

Diagnosis Lupus is notoriously difficult to diagnose. Many cases are not diagnosed until the patient has suffered irreversible kidney damage; for patients who do not have organ-threatening disease, diagnosis takes an average of two years of searching among physicians and conditions. The telltale erythematous skin lumps or rashes that give lupus erythematosus the latter half of its name eventually appear in 90% of systemic lupus patients and all discoid lupus patients, but may not appear early enough in the course of the disease to guarantee timely diagnosis. Additionally, no single lab test can confirm lupus, although certain antibody tests can help to distinguish lupus from other diseases. Diagnosis of systemic lupus is based on a list of 11 criteria listed by the American College of Rheumatology. If four or more of the 11 criteria are met, a patient is deemed to have systemic lupus. The criteria include discoid or macular rash (often in a classic facial butterfly pattern across the nose and cheeks), photosensitivity, ulcers in the mouth, kidney dysfunction, and the presence of various blood factors such as anti-DNA antibody or anti-nuclear antibody (antibody that targets cell nuclei). Approximately 15% of diagnoses of lupus may be misdiagnoses of other disorders, including fibromyalgia, seronegative spondyloarthropathies such as ankylosing spondylitis or Reiter’s syndrome, autoimmune thyroiditis, and multiple sclerosis. Although diagnosis of lupus cerebritis is particularly difficult, even if a patient has lupus, this does not necessarily mean that the neurological symptoms are due to lupus. Imaging studies cannot necessarily distinguish lupus cerebritis, although magnetic resonance imaging (MRI) studies are considered helpful. Positron emission tomography (PET) imaging has a high sensitivity to changes in the brain resulting from lupus cerebritis.

Treatment team As with other neurological diseases in which the spectrum of symptoms varies widely, the treatment team must be designed for each individual case of lupus. A dermatologist will be involved if skin lesions are present; a neurologist, if cognitive loss is a possibility; a nephrologist will monitor kidney function; and a rheumatologist is often involved because of the frequency of joint pain. Other specialists will be needed depending on what organ systems are affected.

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• Discoid or cutaneous lupus erythematosus. This variety of lupus is less severe, in that it attacks the skin only. However, it can be disfiguring, often attacking the skin of the face. The term discoid is derived from the round (disc-shaped) lesions that appear on the skin. About 10–15% of lupus patients have cutaneous lupus.

Lupus

Treatment

Clinical trials

There is no known cure for lupus. However, there are numerous interventions designed to lessen the severity of the disease. These interventions can be classed as pharmacologic (drug-based) or nonpharmacologic. Pharmacologic interventions (drug therapies) Five categories of medication are used to treat systemic lupus patients: sunscreens and steroid lotions, nonsteroidal anti-inflammatory drugs (NSAIDs, e.g., acetaminophen or ibuprofen), corticosteroids (e.g., prednisone to suppress the autoimmune response and control inflammation), anti-malarial drugs, and cytotoxic agents (i.e., chemotherapy drugs that are used for cancer, such as methotrexate, azathioprine, and cyclophosphamide). Cytotoxic agents are used in order to decrease steroid dosage. Anticoagulants (blood thinners) may also be prescribed. For patients with non-organ-threatening disease, the antimalarial drug hydroxychloroquine is often prescribed; prednisone is often prescribed in cases of organ-threatening disease. New lupus drugs are under investigation; with recent increases in knowledge about the genetic and molecular basis of autoimmune disorders, including lupus, pharmacological treatment breakthroughs are possible at any time. Nonpharmacologic (non-drug) interventions All persons with lupus should guard against exposure to the sun and use protective clothing, sunscreen, and common sense when going outdoors. Adequate exercise can protect against fatigue, obesity, osteoporosis (weakening of the bones), and hyperlipidemia (excessive fats in the blood plasma). In some cases, dietary restrictions may be helpful, including especially the avoidance of food allergens and foods that may trigger lupus symptoms (such as alfalfa seeds). Vitamins, minerals, and dietary fatty acids have been shown to moderate lupus symptoms in some cases. On the other hand, some dietary supplements such as melatonin and Echinacea can worsen symptoms of some autoimmune diseases. For lupus cerebritis, therapy choices include all the above options for alleviating the disorder throughout the rest of the body. Drug therapy can also include psychotropic medications such as antipsychotics, antidepressants, and benzodiazepines to stabilize mood, if this is affected. Unfortunately, long-term use of corticosteroids, one of the mainstays of pharmacological lupus treatment, may itself cause psychiatric symptoms. Experimental investigation of pheresis of cerebrospinal fluid for treatment of lupus cerebritis (cerebrospinal fluid is withdrawn from, filtered, and returned to the patient) was begun in the early 1990s. 504

As of mid-2004, approximately 25 lupus-related clinical trials were in progress, including investigations of monoclonal antibody therapy, the genetics of lupus, quality-of-life improvement, ultraviolet light therapy, stem-cell transplantation therapy, the mechanisms of kidney and brain damage, and many other aspects of lupus. Updated information on these trials can be found at the National Institutes of Health clinical trials website at for up-to-date information.

Prognosis Prognosis for the individual patient depends on the severity of the disease process. Lupus can be fully compatible with a normal lifespan, or can result in fatal organ failure, depending upon the progression of the disorder in each individual. Before corticosteroids became available, half of all patients with systemic lupus died within two years. Today, half of systemic lupus patients with organ-threatening complications survive for 20 years or longer. However, most systemic lupus patients eventually die from infections or from heart disease complicated by long-term use of corticosteroids. There is some evidence that lupus may spontaneously resolve in part or whole, or resolve in response to treatment, in some lupus patients who have had the disease long term (i.e., 10 years or more).

Special concerns Psychological counseling may be helpful, given that a diagnosis of lupus is life altering, and stress and frustration can enhance symptoms while searching for a diagnosis. Genetic counseling may be appropriate, as children of women with lupus have a 10% chance of developing lupus if female and 2% if male, while 20% of offspring overall will develop an autoimmune disorder of some type. Resources BOOKS

Phillips, Robert H., et al. Coping with Lupus: A Practical Guide to Alleviating the Challenges of Systemic Lupus Erythematosus, 3rd ed. New York: Avery Penguin Putnam, 2001. Wallace, Daniel J. The Lupus Book: A Guide for Patients and Their Families. New York: Oxford Press, 2000. PERIODICALS

Marshall, Eliot. “Lupus: Mysterious Disease Holds Its Secrets Tight.” Science (April 26, 2002). Nickens, Candice. “Treating Systemic Lupus Erythmatosus.” Minority Health Today (July 1, 2000). Rushing, Jill D. “Managing Organ-threatening Systemic Lupus Erythematosus.” MedSurg Nursing (December 1, 2003).

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OTHER

“NINDS Neurological Sequelae Of Lupus Information Page.” National Institute of Neurological Disorders and Stroke. April 24, 2004 (June 1, 2004). . ORGANIZATIONS

Lupus Foundation of America. 2000 L Street, N.W., Suite 710, Washington, DC 20036. (202) 349-1155; Fax: (202) 3491156. .

Larry Gilman

burgdorferi can penetrate the central nervous system relatively early in the course of the infection without causing any neurologic symptoms. It can also remain in the person’s skin for years without causing symptoms. Lyme disease is a systemic illness, which means that it affects all parts of the body. The most commonly affected areas and organs, however, are the skin, nervous system, heart, joints, and eye. The symptoms of Lyme disease typically emerge in three stages. It is possible for a person to contract Lyme disease more than once; having the disease does not lead to immunity.

Demographics

❙ Lyme disease Definition

Lyme disease, which is also known as Lyme borreliosis, is an infection transmitted by the bite of deer ticks carrying the spirochete (spiral-shaped bacterium) Borrelia burgdorferi. The disease was named for Lyme, Connecticut, the town where it was first diagnosed in 1975 after a puzzling outbreak of juvenile arthritis. The organism that causes the disease was identified in 1982 and named for its discoverer, Willy Burgdorfer.

Description Lyme disease is classified as a zoonosis, which means that it is a disease of animals that can be transmitted to humans under natural conditions; it cannot be transmitted person-to-person. B. burgdorferi is carried by infected deer ticks (more precisely known as black-legged ticks) and passed to humans or household pets when they are bitten by the ticks. In the United States, the white-footed mouse is the usual host of immature (nymphal and larval) ticks, while deer are the most common hosts of the adult ticks. In Europe, sheep are the usual hosts of adult infected ticks. Adult black-legged ticks are hard to detect because of their small size; an adult male tick, for example, is about 0.039 in (1 mm) long. An adult female is slightly larger, about 0.051 in (1.3 mm) long. Ticks feed on their hosts by piercing the skin and slowly sucking blood through the broken tissue. The spirochete enters the host as the tick fills itself with blood. After the spirochete has been introduced into the person’s skin, it may be destroyed by the body’s defense mechanisms. If it is not eliminated, it may either remain in the skin or spread throughout the body through the lymphatic system or the bloodstream. B. burgdorferi can spread to the heart, joints, or central nervous system once it has gained access to the person’s circulation. Studies show that B.

The risk of getting Lyme disease depends more on geographical location and the amount of time spent outdoors in tick-infested areas than on age, sex, or race per se, although about 25% of cases in the United States are reported in children younger than 14. Cases of Lyme disease have been reported in 49 of the 50 states; however, 92% of the 17,730 cases reported to the Centers for Disease Control and Prevention (CDC) in 2000 were from only nine states (Connecticut, Rhode Island, New York, Pennsylvania, Delaware, New Jersey, Maryland, Massachusetts, and Wisconsin). The disease is also found in Scandinavia, continental Europe, the countries of the former Soviet Union, Japan, and China; in addition, it is possible that it has spread to Australia. Lyme disease is seasonal in occurrence. In the United States, humans are most likely to be infected from May through August, when the ticks are most active and people are spending more time outdoors. The number of cases reported in the United States continues to increase each year; the CDC attributes this increase to the growing size of the deer herd and the geographical spread of infected ticks rather than to improved diagnosis. In addition, some epidemiologists believe that the actual incidence of Lyme disease in the United States may be five to ten times greater than that reported by the CDC. The reasons for this difference include the narrowness of the CDC’s case definition as well as frequent misdiagnoses of the disease.

Causes and symptoms Lyme disease itself is caused by a bacterium known as Borrelia burgdorferi, which enters the skin through the bite of an infected tick belonging to the genus Ixodes. In Europe, the disease is caused by related species known as B. afzinii and B. garinii. Currently, scientists do not completely understand exactly how B. burgdorferi produces the variety of symptoms that characterize Lyme disease. Some symptoms are

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“Systemic Lupus Erythematosus: Guidelines for Control.” Consultant (February 1, 2000).

Lyme disease Lyme disease. The image shows the side of a leg at the calf with an insect bite enclosed by a distinctive, slightly raised red ring. The rash is called erythema chronicum migrans. (© 1993 Science Photo Library. Custom Medical Stock Photo. Reproduced by permission.)

directly caused by the spirochete, but others may result from the body’s immune response to the organism.

and fatigue. Nausea and vomiting or sore throat occur in some patients, but are less common symptoms.

The symptoms of Lyme disease are typically divided into three stages: early localized, early disseminated, and late. Neurologic complications are most common in disseminated and late-stage Lyme disease.

EARLY DISSEMINATED DISEASE Early disseminated Lyme disease is characterized by ongoing fatigue; arthritis-like pains in the joints; a headache that comes and goes; inflammation of the tendons and their protective sheaths (synovitis); and red or itchy eyes (conjunctivitis). It is common for the aches and pains in muscles and joints to move from one part of the person’s body to another. About 8% of people with Lyme disease develop cardiac complications, which may include heart block and inflammation of the walls of the heart (myocarditis).

EARLY LOCALIZED DISEASE Early symptoms of Lyme disease include low-grade fever and erythema migrans, or EM, a red spot or patch on the skin that is found in about 75% of patients with Lyme disease. The initial spot is usually found on the arms, legs, armpits, or trunk within 3–32 days after the tick bite. Erythema migrans often has a ringlike or “bull’s-eye” appearance, with the bite itself in the center of the affected area, surrounded by a ring of reddened and inflamed skin. The ring grows outward around the central lesion, sometimes growing as large as 27 in (70 cm) in diameter. Secondary EM lesions appear in about 20% of patients. The rash does not usually itch or burn, and typically fades in a few weeks even if untreated.

Other symptoms of early-stage Lyme disease include flu-like muscular aches and pains, headache, a stiff neck,

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Neurologic symptoms in early disseminated Lyme disease affect about 15% of people, usually within a few weeks to months after the onset of EM. The following may be the first symptoms in people who did not develop EM, however: • Bell’s palsy. This refers to weakness or paralysis of the facial muscles caused by inflammation or swelling of the seventh cranial nerve. People with facial palsy caused by Lyme disease may be affected on both sides of the face.

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Babesiosis A disease caused by protozoa of the genus Babesia characterized by a malaria-like fever, anemia, vomiting, muscle pain, and enlargement of the spleen. Babesiosis, like Lyme disease, is carried by a tick. Bell’s palsy Facial paralysis or weakness with a sudden onset, caused by swelling or inflammation of the seventh cranial nerve, which controls the facial muscles. Disseminated Lyme disease sometimes causes Bell’s palsy. Cerebrospinal fluid A clear fluid found around the brain and spinal cord and in the ventricles of the brain. Disseminated Scattered or distributed throughout the body. Lyme disease that has progressed beyond the stage of localized EM is said to be disseminated. Erythema migrans (EM) A red skin rash that is one of the first signs of Lyme disease in about 75% of patients.

This symptom may be important in diagnosis, as Bell’s palsy caused by other disorders typically affects only one side of the face. • Radiculoneuropathy. This is the medical term for disease affecting nerves and nerve roots. In Lyme disease, neuropathy often takes the form of abnormal sensations (paresthesias) in the hands or feet. • Meningoencephalitis. This refers to inflammation of the brain tissue and the protective membranes that cover it (the meninges). This complication of Lyme disease often causes sleep disturbances, memory problems, difficulty concentrating, mood swings, headache, ataxia (loss of muscular coordination), paresis (mild paralysis), and disturbances in the person’s deep tendon reflexes. To test these reflexes, or involuntary responses of certain muscles to a stimulus, the physician gently taps with a small hammer below the person’s kneecap, behind the elbow, over the Achilles tendon at the back of the heel, and over the biceps and triceps muscles in the upper arm. The deep tendon reflexes are often weakened or asymmetrical in people with meningoencephalitis related to Lyme disease. LATE DISEASE The most common symptom of late disseminated Lyme disease is swelling and pain in a few large weight-bearing joints, most often the knee. The affected joints are typically much more swollen than painful, but the arthritis may be accompanied by low-grade fever

Lyme borreliosis Another name for Lyme disease. Prophylactic Treatment given to protect against or ward off disease. Many doctors give antibiotics to patients who have been bitten by ticks as a prophylactic measure against Lyme disease. Radiculoneuropathy Disease of the nerve roots and nerves. Spirochete A bacterium shaped like a loosely coiled spiral. The organism that causes Lyme disease is a spirochete. Vector An animal carrier that transfers an infectious organism from one host to another. The vector that transmits Lyme disease from wildlife to humans is the deer tick or black-legged tick. Zoonosis (plural, zoonoses) Any disease of animals that can be transmitted to humans under natural conditions. Lyme disease and babesiosis are examples of zoonoses.

and fatigue. Lyme-related arthritis develops within weeks to months after the initial eruption of erythema migrans. About 10% of people diagnosed with Lyme disease develop chronic arthritis of the knee. A late-stage complication of Lyme disease that affects the skin is acrodermatitis chronica atrophicans, a disorder in which the skin on the person’s lower legs or hands becomes inflamed and paper-thin. This disorder is seen more frequently in Europe than in the United States. People with late-stage Lyme disease may develop a neurologic disorder characterized by personality changes and problems with thinking or memory that persist in spite of antibiotic treatment. This syndrome has been called persistent Lyme disease, or PLD. One study of 33 patients diagnosed with PLD found that the most common symptoms were headache (36.4% of patients); memory problems (27.3%); insomnia (33.3%); problems with gait and coordination (36.4%); and impaired deep tendon reflexes (9%). Children with PLD have difficulty getting along with classmates in school as well as making academic progress, and are at increased risk of developing long-term psychiatric disturbances.

Diagnosis Early diagnosis and prompt treatment are critical to preventing the neurologic complications of Lyme disease.

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Lyme disease

Patient history and symptoms The diagnosis of Lyme disease is complicated by the fact that about 25% of patients do not develop the characteristic rash. It is important for the doctor to determine the likelihood of Lyme disease by taking a careful history of exposure to ticks, as only about 25% of patients recall being bitten. In addition to the history, the doctor will examine the patient for the following symptoms: • Erythema migrans. When present, EM has a characteristic “bull’s-eye” pattern. In addition, the bite location is often significant; tick bites are more frequently found in such body folds as the armpits or on areas on the trunk near elastic bands in bra straps or underwear. • Fever. The fever that accompanies early Lyme disease is usually low; a high fever indicates either concurrent infection with babesiosis or a different diagnosis altogether. • Absence of digestive or respiratory symptoms. • Presence of fatigue, headache, and muscle or joint pains. Laboratory tests Blood testing is not considered necessary if the patient has EM, a history of exposure to ticks, and other indications of a high likelihood of Lyme disease. Moreover, it is difficult to culture B. burgdorferi from human tissues and body fluids. Timing is another important factor in interpreting blood tests for Lyme disease; patients in the early stages of the disease may continue to test negative for several weeks after being infected. Blood testing is, however, recommended for patients with Bell’s palsy or myocarditis. The CDC advises doctors to perform a twostep blood test: a screening ELISA test, followed by a Western blot test for confirmation. Polymerase chain reaction (PCR) testing may not be available in all hospitals, but can be used to detect the DNA of B. burgdorferi in fluid drawn from the joints of untreated patients with late-stage symptoms. Imaging studies Imaging studies are rarely used to diagnose Lyme disease with the exception of late-stage arthritis. X rays of patients with Lyme-related arthritis usually show considerable swelling of soft tissue; erosion of bone or cartilage also appears in a small minority of these patients.

Treatment team Patients are usually treated initially by an emergency physician (if they have gone to an emergency room to have the tick removed) or by a primary care physician (PCP). The PCP may consult a neurologist, dermatologist, or infectious disease specialist to confirm the diagnosis or

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advise about medications, particularly in cases of chronic or late-stage disease.

Treatment Initial treatment Immediate removal of an attached tick is the first step in treatment for people who know they have been bitten. Because black-legged ticks are slow feeders, it takes about 36 hours for B. burgdorferi to make its way into the body; infection is unlikely if the tick is removed within 24 hours of attachment. People who find ticks on themselves should not use a hot match, petroleum jelly, nail polish, or similar items to remove the tick. They should use fine-tipped tweezers, grasp the tick as close to the skin as possible, and pull the tick away from the skin with a steady motion. The area should then be cleansed with an antiseptic. If the person has been bitten in an area with a high percentage of infected ticks, the doctor will usually prescribe a prophylactic (disease-preventing) course of antibiotics. The usual dosage is 10 days of oral amoxicillin, doxycycline, or cefuroxime, although a study published in 2001 reported that a single 200-mg dose of doxycycline is also effective. Aspirin or NSAIDs may be given to relieve fever, aching muscles, and other flu-like symptoms of early Lyme disease. Treatment of disseminated disease and neurologic complications Patients who have developed heart block as a complication of disseminated Lyme disease may require a temporary pacemaker. Those with swollen knee joints may need to have excess fluid removed by aspiration, a procedure in which the doctor withdraws the fluid through a fine needle. Patients with Bell’s palsy may be given oral antibiotics for 21–30 days. Patients who have neurologic symptoms together with Lyme-related arthritis are usually treated with intravenous ceftriaxone.

Recovery and rehabilitation Most patients with neurologic complications of Lyme disease recover completely following treatment with antibiotics. Those who do not respond are usually given an additional course of antibiotics. As of 2003, however, treatment recommendations for central nervous system (CNS) complications of Lyme disease are still evolving, and there is ongoing disagreement among specialists regarding the effectiveness of various treatments for PLD.

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As of October 2003, the National Institute of Neurological Disorders and Stroke (NINDS) is recruiting patients for a 24-week treatment study of persistent Lyme disease (PLD). The investigators will be using brain imaging (MRI and PET scans) to study the effects of intravenous antibiotic treatment on the neurologic symptoms of PLD. Two other trials are recruiting patients with Lyme disease in order to study the immune system’s response to the disorder and to evaluate various treatment regimens.

Prognosis Patients who are treated early with antibiotics and take their medications on schedule should recover completely from Lyme disease. Most long-term effects of the infection result from misdiagnosis or delayed treatment. Co-infection with such other tick-borne diseases as babesiosis and ehrlichiosis may lead to treatment failures or more severe symptoms. The few fatalities reported with Lyme disease occurred in patients who had also contracted babesiosis. Neurologic symptoms of early disseminated Lyme disease may last for several months but usually resolve completely. Late neurologic complications of Lyme disease, however, may not respond to antibiotic therapy, particularly if diagnosis and treatment were delayed.

Special concerns A vaccine for Lyme disease known as LYMErix was available from 1998 to 2002, when it was removed from the United States market. The decision was influenced by reports that LYMErix may be responsible for neurologic complications in vaccinated patients. Researchers from Cornell-New York Hospital presented a paper at the annual meeting of the American Neurological Association in October 2002 that identified nine patients with neuropathies linked to vaccination with LYMErix. In April 2003, the National Institute of Allergy and Infectious Diseases (NIAID) awarded a federal grant to researchers at Yale University School of Medicine to develop a new vaccine against Lyme disease. Resources BOOKS

“Bacterial Diseases Caused by Spirochetes: Lyme Disease (Lyme Borreliosis).” Section 13, Chapter 157 in The Merck Manual of Diagnosis and Therapy, edited by Mark

H. Beers, MD, and Robert Berkow, MD. Whitehouse Station, NJ: Merck Research Laboratories, 2002. PERIODICALS

Adams, H. B., G. A. Blasko, and L. A. DiDomenico. “An Unusual Case of Bilaterally Symmetrical Neuropathic Osteoarthropathy of the Midfoot as a Result of Lyme Disease-Induced Peripheral Neuropathy: A Case Report.” Foot and Ankle International 23 (February 2002): 155–157. Coyle, P. K. “Lyme Disease.” Current Neurology and Neuroscience Reports 2 (November 2002): 479–487. Edlow, Jonathan A., MD. “Tick-Borne Diseases, Lyme.” eMedicine, 13 December, 2002 (February 20, 2004). . Gustaw, K., K. Beltowska, and M. M. Studzinska. “Neurological and Psychological Symptoms after the Severe Acute Neuroborreliosis.” Annals of Agricultural and Environmental Medicine 8 (2001): 91–94. Tager, F. A., B. A. Fallon, J. Keilp, et al. “A Controlled Study of Cognitive Deficits in Children with Chronic Lyme Disease.” Journal of Neuropsychiatry and Clinical Neurosciences 13 (Fall 2001): 500–507. OTHER

National Institute of Neurological Disorders and Stroke (NINDS) Fact Sheet. Bell’s Palsy. Bethesda, MD: NINDS, 2003. NINDS Information Page. Neurological Complications of Lyme Disease. Bethesda, MD: NINDS, 2003. WEBSITES

Centers for Disease Control and Prevention, Division of Vector-Borne Infectious Diseases. CDC Lyme Disease Home Page. (February 20, 2004.) . ORGANIZATIONS

Centers for Disease Control and Prevention (CDC). 1600 Clifton Road, NE, Atlanta, GA 30333. (800) 311-3435. [email protected]. . Lyme Disease Foundation. One Financial Plaza, Hartford, CT 06103. (860) 525-2000 or (860) 525-TICK or (800) 886LYME. [email protected]. . National Institute of Allergy and Infectious Diseases (NIAID). 31 Center Drive, Room 7A50 MSC 2520, Bethesda, MD 20892. (301) 496-5717. . NIH Neurological Institute. P. O. Box 5801, Bethesda, MD 20824. (301) 496-5751 or (800) 352-9424. .

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Clinical trials